Drinking Water: Information on the Quality of Water Found at Community
Water Systems and Private Wells (Chapter Report, 06/12/97,
GAO/RCED-97-123).
Pursuant to a congressional request, GAO provided information on the
quality of drinking water found at community water systems and private
wells, focusing on: (1) what is known about the quality of drinking
water from community water systems and private wells; and (2) what
factors influence the quality of drinking water from these sources.
GAO noted that: (1) much more is known about the quality of drinking
water form community water systems than from private wells; (2) to meet
the Safe Drinking Water Act's requirements, community water systems must
periodically monitor their water for contaminants, such as total
coliform bacteria, pesticides, naturally occurring elements, and
industrial solvents; (3) in the six states that GAO reviewed, compliance
data for fiscal years 1993 through 1996 show that violations of the
standard for total coliform bacteria were the most common, being
reported by 3 to 6 percent of the more than 17,000 community water
systems; (4) a sizable number of systems, although a small percentage of
the total, violated standards for radiological contaminants, nitrate,
and the herbicide atrazine; (5) violations of other standards were few;
(6) for private wells, the available data on water quality are, for the
most part, limited to data on total coliform bacteria and nitrate; (7)
these data have been collected for special studies, in response to state
and local testing requirements for new wells, and through voluntary
testing requested by well owners; (8) while these data are not always
representative or unbiased, those that are have shown rates of bacterial
contamination as high as 42 percent and rates of excessive nitrate as
high as 18 percent; (9) less extensive data on two commonly used
herbicides show much lower levels of contamination in private wells;
(10) several factors influence the quality of drinking water obtained
from community water systems and private wells; and (11) these factors
include the condition of the source from which the drinking water is
extracted, the use of construction standards and other controls designed
to ensure that new water systems and private wells are properly
constructed and protected from potential sources of contamination, and
ongoing oversight and maintenance activities, such as periodic testing
and inspections, that help determine whether the water will continue to
be safe.
--------------------------- Indexing Terms -----------------------------
REPORTNUM: RCED-97-123
TITLE: Drinking Water: Information on the Quality of Water Found
at Community Water Systems and Private Wells
DATE: 06/12/97
SUBJECT: Water quality
Water pollution control
Safety standards
Water supply management
Safety regulation
Potable water
Infectious diseases
Hazardous substances
IDENTIFIER: California
Illinois
Nebraska
New Hampshire
North Carolina
Wisconsin
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Cover
================================================================ COVER
Report to Congressional Requesters
June 1997
DRINKING WATER - INFORMATION ON
THE QUALITY OF WATER FOUND AT
COMMUNITY WATER SYSTEMS AND
PRIVATE WELLS
GAO/RCED-97-123
Drinking Water Quality
(160362)
Abbreviations
=============================================================== ABBREV
CDC - Centers for Disease Control and Prevention
EPA - Environmental Protection Agency
GAO - General Accounting Office
MCL - maximum contaminant level
SDWA - Safe Drinking Water Act
Letter
=============================================================== LETTER
B-276974
June 12, 1997
The Honorable J. Dennis Hastert
The Honorable Bill Paxon
House of Representatives
As requested, this report provides information on (1) what is known
about the quality of drinking water from community water systems and
private wells in six states and (2) what factors influence the
quality of drinking water from these sources. The report contains a
recommendation designed to help ensure that owners of private wells
are better informed of potential contamination problems whenever
groundwater-based community systems detect contamination that may
also be present at nearby private wells.
As arranged with your offices, unless you publicly announce its
contents earlier, we will make no further distribution of this report
until 30 days after the date of this letter. At that time, we will
send copies to the appropriate congressional committees; the
Administrator, Environmental Protection Agency; and the Director,
Office of Management and Budget. We will also make copies available
to other interested parties upon request. Major contributors to this
report are listed in appendix III.
Stanley Czerwinski
Associate Director, Environmental
Protection Issues
EXECUTIVE SUMMARY
============================================================ Chapter 0
PURPOSE
---------------------------------------------------------- Chapter 0:1
The vast majority of U.S. households get their drinking water from
community water systems regulated under the federal Safe Drinking
Water Act. These water systems must comply with a variety of federal
and state requirements relating to their construction, the periodic
monitoring of their water quality, inspections, and other matters.
The remaining households do not have access to community water
systems and rely primarily on private domestic wells that are not
subject to the act but may be subject to state and local
requirements.
To learn more about the quality of drinking water, Representatives J.
Dennis Hastert and Bill Paxon and former Representative Blanche
Lambert-Lincoln asked GAO to provide them with information on (1)
what is known about the quality of drinking water from community
water systems and private wells and (2) what factors influence the
quality of drinking water from these sources. To meet these
objectives, GAO gathered data from six states selected on the basis
of such factors as the number or percentage of households that use
private wells and the amount of information available on water
quality from private wells. The states are California, Illinois,
Nebraska, New Hampshire, North Carolina, and Wisconsin.
BACKGROUND
---------------------------------------------------------- Chapter 0:2
The Safe Drinking Water Act, enacted in 1974, requires the
Environmental Protection Agency (EPA) to establish drinking water
standards for the nation's nearly 56,000 community water systems.
The act also requires water systems to monitor the water delivered to
consumers to determine whether it meets the standards. EPA generally
grants to the states the responsibility for enforcing these standards
and for overseeing community water systems. In both 1986 and 1996,
the Congress amended the act to revise the standard-setting process;
strengthen enforcement authority; and/or add other requirements for
EPA, the states, and water systems.
An estimated 15 million households that are not served by community
water systems get their drinking water from private, domestic wells.
Although private wells are not covered by the Safe Drinking Water
Act, state and local governments may establish their own requirements
for constructing, testing, inspecting, and otherwise regulating these
wells. Other federal and state laws' provisions are designed to
protect groundwater and/or surface water from contamination. Both
private wells, which are generally supplied by groundwater, and
community water systems, which are supplied by either groundwater or
surface water, may be affected by these laws.
RESULTS IN BRIEF
---------------------------------------------------------- Chapter 0:3
Much more is known about the quality of drinking water from community
water systems than from private wells. To meet the Safe Drinking
Water Act's requirements, community water systems must periodically
monitor their water for contaminants, such as total coliform
bacteria, pesticides, naturally occurring elements, and industrial
solvents. In the six states that GAO reviewed, compliance data for
fiscal years 1993 through 1996 show that violations of the standard
for total coliform bacteria were the most common, being reported by 3
to 6 percent of the more than 17,000 community water systems. A
sizable number of systems (although a small percentage of the total)
violated standards for radiological contaminants, nitrate, and the
herbicide atrazine. Violations of other standards were few.
For private wells, the available data on water quality are, for the
most part, limited to data on total coliform bacteria and nitrate.
These data have been collected for special studies, in response to
state and local testing requirements for new wells, and through
voluntary testing requested by well owners. While these data are not
always representative or unbiased, those that are have shown rates of
bacterial contamination as high as 42 percent and rates of excessive
nitrate as high as 18 percent. Less extensive data on two commonly
used herbicides show much lower levels of contamination in private
wells.
Several factors influence the quality of drinking water obtained from
community water systems and private wells. These factors include (1)
the condition of the source from which the drinking water is
extracted; (2) the use of construction standards and other controls
designed to ensure that new water systems and private wells are
properly constructed and protected from potential sources of
contamination; and (3) ongoing oversight and maintenance activities,
such as periodic testing and inspections, that help determine whether
the water will continue to be safe.
PRINCIPAL FINDINGS
---------------------------------------------------------- Chapter 0:4
DATA ON CONTAMINATION ARE
EXTENSIVE FOR COMMUNITY
WATER SYSTEMS AND LIMITED
FOR PRIVATE WELLS
-------------------------------------------------------- Chapter 0:4.1
Under the Safe Drinking Water Act, community water systems are
required to monitor their water for up to 72 specific contaminants,
including bacteria, pesticides, industrial solvents, and other
chemical and radiological compounds. The frequency of the required
monitoring ranges from daily to once every 9 years, depending on the
type of contaminant, the population served by the water system, the
source of the water, and the presence of contaminants in past
samples. Community water systems may also have to employ treatment
techniques to prevent unsafe levels of up to nine other contaminants.
Four of the six states reviewed by GAO do not require any testing at
private wells; the other two states require testing for bacteria, and
one of these states requires testing for nitrate before new wells are
put into service. In some instances, local governments and lending
institutions require limited testing at new wells. Other data on the
quality of private well water are available because testing was
initiated by well owners or special studies were conducted.
In total, community water systems in the six states reviewed by GAO
exceeded the standard at least once for 25 of the regulated
contaminants during fiscal years 1993 through 1996. By far the most
common problem was contamination with total coliform bacteria, from a
low of 577 systems (3.3 percent of 17,443) reporting at least one
violation in 1996 to a high of 1,035 (5.7 percent of 17,976) doing
the same in 1993. The next most common problem was exceeding the
standard for naturally occurring combined radium; an average of 129
systems (no more than 0.8 percent per year) reported such violations
over the 4 years. Other standards violated by a number of systems
over the 4 years were for nitrate (58 systems per year, on average),
naturally occurring alpha emitters (53 systems, on average), and the
herbicide atrazine (22 systems, on average). Few community water
systems reported violations for the other 20 contaminants.
Because water quality is not routinely monitored at private wells as
it is at community water systems, the data available for private
wells are limited. Through both representative and unrepresentative
methods, such data have been gathered for special studies, tests
required by state and local governments, and voluntary tests
requested by well owners. In the six states reviewed by GAO, the
available data were primarily for total coliform bacteria and
nitrate, and only limited data existed for pesticides, heavy metals,
and volatile organic compounds. Nearly all of the data show that
contamination with total coliform bacteria is common for private
wells, that excessive nitrate concentrations range from common to
rare, and that contamination with herbicides is rare, as shown by the
following. A 1994 survey led by the Centers for Disease Control and
Prevention (CDC) collected data on total coliform bacteria and
nitrate concentrations from a sample of geographically distributed
private wells in three of the six states included in GAO's study.
Total coliform bacteria in excess of the standard were detected in
46, 37, and 23 percent of the wells tested in Illinois, Nebraska, and
Wisconsin, respectively. Nitrate was detected in concentrations
exceeding EPA's standard in 15, 15, and 7 percent of the wells tested
in the three states, respectively. The study reported the herbicide
atrazine at levels above EPA's standard at no more than 0.2 percent
of the wells in these three states.
Community water systems and private wells located in the same general
area may use the same source of groundwater. Thus, according to EPA
and state drinking water officials, some of the contaminants detected
in community systems are likely to be present in nearby private
wells. This is most likely to be true for contaminants, such as
nitrate and various pesticides, that have leached into the
groundwater after long-term application on the land. However,
community water systems are required to treat their water when
necessary or to take other actions to avoid violating water quality
standards.
In 1975, under authority of the Safe Drinking Water Act, EPA began
requiring community water system owners to inform their customers
whenever their systems exceed the standard for a regulated
contaminant. The 1996 amendments require that after August 1998,
community water system owners annually inform their customers of all
detections of contaminants. Water quality data from testing
community water systems that use groundwater may be useful to private
well users if they derive groundwater from the same source,
particularly because private well users rarely test their water for
most contaminants regulated by the act. However, community water
system owners are required to notify only their customers and not
private well users whenever contamination is detected in groundwater.
Hence, private well users may not be aware of nearby contamination
that could affect their water supply.
CONDITION OF SOURCE,
STANDARDS FOR WELL
CONSTRUCTION, AND OTHER
FACTORS INFLUENCE WATER
QUALITY
-------------------------------------------------------- Chapter 0:4.2
The condition of the water source can significantly affect the
quality of drinking water supplied by community water systems and
private wells, particularly if the water is untreated. Community
systems are much more likely than private well users to treat their
water for contaminants that pose health risks. In addition, private
wells are typically shallower than the wells in community systems and
are more likely to tap into contamination that has leached into
groundwater from the surface.
Another key factor influencing water quality is the nature of the
controls in place to help ensure that new drinking water sources,
including both community systems and private wells, are properly
constructed and protected from potential contamination. All six of
the states reviewed by GAO have established construction standards
and siting requirements that specify minimum distances between the
water source and potential sources of contamination for both
community water systems and private wells. As regulated public water
supplies, new or substantially modified community systems must
undergo a rigorous approval process. However, states and local
communities vary in the extent to which they impose controls over new
private wells.
Ongoing oversight and maintenance activities, such as the periodic
monitoring of water quality and routine inspections--and the extent
to which such activities trigger corrective action--also influence
water quality. As noted earlier, community water systems are subject
to extensive testing, and states periodically conduct comprehensive
inspections of water systems' design, operation, and maintenance.
However, the primary responsibility for the ongoing oversight and
maintenance of private wells rests with individual homeowners; none
of the states GAO visited requires testing at existing wells or
conducts routine inspections. For example, because of financial
constraints, New Hampshire officials have inspected only four or five
of the estimated 50,000 private wells constructed over the past 12
years. When contamination is detected at community systems, states
can compel corrective action. But identifying and correcting
contamination problems at private wells is generally left to the
discretion of the well owners.
RECOMMENDATION
---------------------------------------------------------- Chapter 0:5
To help ensure that private well users are better informed of
potential contamination problems and associated health risks, GAO
recommends that the Administrator, Environmental Protection Agency,
explore options that would provide such well users with information
on how to learn more about the quality of their drinking water and
the steps they can take to protect the source of their drinking water
from contamination. For example, state and/or local health agencies
could use the local media to alert private well users to consider
testing their water whenever the testing of a groundwater-supplied
community water system detects contamination that could potentially
be present in the same geologic formation supplying nearby private
wells.
AGENCY COMMENTS
---------------------------------------------------------- Chapter 0:6
GAO provided a draft of this report to EPA, CDC, and the six states
that GAO reviewed. GAO obtained comments from EPA officials,
including the Director of the Implementation and Assistance Division
of the Office of Ground Water and Drinking Water, and CDC officials
from the National Center for Environmental Health and the National
Center for Infectious Diseases. GAO also obtained comments from
representatives of the state agencies responsible for overseeing
drinking water quality. The federal agencies and states generally
agreed with the information presented in the report. They did offer
updated information or technical comments, which GAO incorporated
throughout the report, as appropriate. EPA, CDC, and the states
agreed with the intent of GAO's recommendation and offered
suggestions for clarifying and expanding it. GAO has revised the
recommendation to give EPA and the states more flexibility in
achieving the goal of increasing the amount of water quality
information available to private well users.
INTRODUCTION
============================================================ Chapter 1
Because safe drinking water is essential to public health, the
quality of the nation's drinking water supply is an issue of national
importance. For the most part, consumers receive drinking water from
either community water systems or private wells. The water, which
may be tapped from groundwater aquifers or surface water bodies, is
vulnerable to a wide range of pollutants from agricultural,
industrial, urban, and residential land uses, as well as natural
causes. In response to these threats, federal, state, and local
governments have put regulatory programs in place to prevent
consumers from drinking contaminated water. However, variations in
the sources of drinking water, in its delivery to consumers, and in
the extent to which its quality is regulated have raised questions
about whether safe drinking water is being consistently delivered to
all citizens.
MOST AMERICANS GET THEIR
DRINKING WATER FROM COMMUNITY
WATER SYSTEMS OR PRIVATE WELLS
---------------------------------------------------------- Chapter 1:1
The vast majority of Americans get their residential drinking water
from one of two categories of delivery systems--community water
systems or private wells. According to the 1990 census, about 84
percent of the nation's 102 million households obtained their
drinking water from community water systems, most of which are
regulated under the Safe Drinking Water Act (SDWA) of 1974.\1 Of the
remaining 16 percent of households, about 15 million received their
drinking water from private wells and about 1 million used small
unregulated water systems.\2 Private wells are not regulated under
SDWA but may be regulated by state and local governments. Other
means of drinking water delivery include SDWA-regulated noncommunity
systems.\3
About 55,600 community water systems operated in the United States in
fiscal year 1995, compared with over 59,000 in fiscal year 1991.
This decline is attributed, at least in part, to the consolidation of
small systems into larger ones. Despite this trend toward
consolidation, about 85 percent of the community systems are small,
serving fewer than 3,300 people.
The National Ground Water Association estimates that over 300,000 new
private wells are drilled each year. There are several reasons why
many Americans obtain their drinking water from private wells. Many
live in sparsely populated rural areas where it is not economically
feasible to install community water systems. Some consumers have put
in private wells to avoid the increasing cost of the water supplied
by community systems, and others simply prefer to control their own
water source.
Most Americans also drink water outside the home, such as at work,
school, and restaurants and while traveling. The source of this
water may be a community water system, a private well, or what is
known under SDWA as a noncommunity system. While noncommunity
systems do not serve residential customers, they must still meet
certain requirements for their operation, water quality monitoring,
and water treatment. The focus of this report is on water consumed
in the home from private wells and regulated community systems. In
this report, the term private well includes the well, the pump, and
the connections leading to the household tap.
--------------------
\1 The U.S. Bureau of the Census defines a community water system as
one that supplies water to five or more housing units. This
definition contrasts with SDWA's, under which a community water
system is one that serves at least 25 year-round residents or has at
least 15 year-round service connections.
\2 A water system that has fewer than 15 service connections or
serves fewer than 25 people is not regulated under SDWA. Such a
system may be regulated by a state or local government. An estimated
1 percent of the population is served by this type of system.
\3 Under SDWA, noncommunity water systems are divided into two
categories: transient and nontransient noncommunity systems.
Transient noncommunity systems serve at least 25 people for more than
60 days a year but do not regularly serve any given 25 people for
more than 6 months a year. Examples include gas stations and
roadside rest areas. Nontransient noncommunity systems regularly
serve at least 25 of the same people for more than 6 months a year.
Examples of these systems are schools, factories, or office
buildings.
SOURCES OF DRINKING WATER ARE
VULNERABLE TO CONTAMINATION
---------------------------------------------------------- Chapter 1:2
Drinking water delivered by community systems and private wells comes
from two sources: surface water and groundwater. Both sources are
vulnerable to contamination. Surface water is drawn from rivers,
lakes, streams, and reservoirs. Groundwater is pumped by wells from
porous rock, sand, or gravel saturated with water that has percolated
down from the surface. Community water systems may rely on
groundwater, surface water, or both, while private wells generally
rely on groundwater. Groundwater and surface water each supply about
50 percent of the country's drinking water.
The quality of the water source can be affected by a variety of
factors, including local land uses, the local geology, and--for
groundwater--the depth of the aquifer from which the water is
extracted. Groundwater is vulnerable to contaminants that filter
down into underground aquifers from the surface; when this occurs,
the water level closest to the surface is affected first. Deeper
levels of an aquifer or areas that are protected by a confining clay
layer are often unaffected by surface contamination. Surface water
is vulnerable to contaminants from runoff, precipitation, air
pollution, and direct discharges from industrial and municipal
facilities.
Local land uses can have a significant impact on groundwater and
surface water. For example, in some agricultural areas, the
long-term application of pesticides and fertilizers has contaminated
underlying groundwater. Near landfills and industrial facilities,
improper waste disposal or chemical spills have also contaminated
groundwater. And man-made contaminants may be introduced into
groundwater by other means. For example, abandoned wells that have
not been properly sealed can serve as conduits for contamination from
the surface. Naturally occurring inorganic compounds--such as
fluoride, arsenic, and various radiological compounds--may also be
present in groundwater, depending on the type and location of
geological formations. The extent and depth of the contamination
that leaches down from the surface can vary with the volume and type
of the contaminant, the permeability of the soil, the amount of
rainfall in the area, and other environmental characteristics.
Surface water has also been affected by contaminated runoff from
agricultural lands and urban areas. Regions that experience greater
rainfall or are prone to flooding are more vulnerable to
contamination from runoff than more arid regions. Other potential
sources of surface water contamination include chemical discharges
from industrial and municipal wastewater treatment facilities and the
atmospheric deposition of heavy metals and other substances contained
in emissions from manufacturing plants and other facilities.
Drinking water contamination can also occur within the distribution
system. For both private wells and community water systems, this
system includes the connections between the well or treatment
facility and the household tap. For example, a breach in the
distribution system could allow bacteria to contaminate drinking
water.
EPA REGULATES COMMUNITY WATER
SYSTEMS AND SETS STANDARDS FOR
THE QUALITY OF DRINKING WATER
---------------------------------------------------------- Chapter 1:3
With the enactment of SDWA in 1974, the Congress established a
national program to ensure that all community water systems meet
minimum standards to protect public health. SDWA directed the
Environmental Protection Agency (EPA) to establish (1) national
drinking water standards or treatment techniques for contaminants
that could adversely affect public health and (2) requirements for
monitoring the quality of drinking water and for ensuring the proper
operation and maintenance of water systems. SDWA also authorizes EPA
to grant primary enforcement authority for the drinking water
program, commonly referred to as "primacy," to states that meet
certain requirements. With EPA's oversight, the states with primacy
enforce the drinking water program's requirements and oversee the
public water systems within their jurisdiction. The states maintain
other oversight activities to ensure that public water systems meet
design, construction, and water quality standards.
For each of the currently regulated contaminants,\4 EPA was required
under SDWA to establish (1) a health-based goal at a level at which
no known or anticipated adverse health effects occur and that allows
an adequate margin of safety and (2) a national primary drinking
water regulation, generally based on the highest allowable
concentration of a contaminant in drinking water, called a maximum
contaminant level (MCL). SDWA required EPA to set the MCL as close
to the health-based goal as feasible, considering the available
technology and costs.\5 EPA was allowed to specify a treatment
technique in lieu of an MCL whenever it was not feasible to measure
the level of a contaminant in drinking water.\6 EPA's
responsibilities in setting standards for the quality of drinking
water were recently modified under the 1996 amendments to SDWA. The
agency now has more flexibility in deciding which contaminants should
be regulated and may give greater consideration to relative costs and
risk-reduction benefits.
EPA currently regulates 81 contaminants that could adversely affect
public health\7 and has established MCLs for 72 of these
contaminants. Community water systems are required to test their
water for the 72 contaminants and take certain corrective actions if
they find levels above an MCL. For the remaining nine contaminants,
EPA requires that community systems use specific treatment techniques
that will reduce contaminants to acceptable levels. Additional
monitoring may be required in conjunction with the use of these
treatment techniques. EPA also sets "secondary" standards for
contaminants that affect the aesthetic quality of drinking water,
such as its taste, odor, and appearance. While the presence of these
contaminants may be unpleasant, EPA does not consider them to be
unhealthy. Both community water systems and private wells may be
affected by the presence of secondary contaminants, and both systems
have treatment options that may improve their water.
--------------------
\4 The contaminants currently regulated under EPA's safe drinking
water program include various inorganic, volatile organic, and
synthetic organic chemicals; radioactive chemicals; and
microbiological contaminants.
\5 On the basis of the legislative history, EPA decides, when
considering costs, whether the technology is reasonably affordable to
regional and large metropolitan water systems.
\6 For some contaminants, the available analytical methods are not
economically or technologically feasible; that is, the methods are
too costly or are not sufficiently accurate or reliable. For these
contaminants, EPA identifies treatments that are effective in
reducing risks.
\7 EPA has set standards for three other contaminants (aldicarb,
aldicarb sulfone, and aldicarb sulfoxide) but is reconsidering these
standards in light of new evidence and has delayed their
implementation.
STATE AND LOCAL GOVERNMENTS SET
REQUIREMENTS FOR PRIVATE WELLS
---------------------------------------------------------- Chapter 1:4
Although private wells are not regulated under SDWA, they are subject
to state and local regulations. For example, state and local
governments may issue permits for, require testing of, or conduct
inspections at private wells. The degree to which state and local
governments have acted to regulate private wells varies from state to
state.
One area of state regulation concerns the construction of private
wells. Over time, different types of wells have been developed to
meet specific geological conditions and to reflect advances in
technology. Not all construction methods are now considered
acceptable, and state requirements can be very specific. (See app.
I for a brief description of common construction methods for wells.)
State and local oversight of private wells not only provides some
degree of consumer protection to well users but also helps protect
the nation's groundwater resources. Inadequately constructed or
improperly abandoned wells can serve as conduits for contamination
from the surface to enter the groundwater.
OTHER FEDERAL, STATE, AND LOCAL
PROGRAMS MAY PROTECT SOURCES OF
DRINKING WATER
---------------------------------------------------------- Chapter 1:5
In addition to the federal, state, and local programs that
specifically address community and private drinking water delivery
systems, other programs are in place to protect source waters from
contamination. Some of these programs are implemented by the states
under the authority of federal statutes, while others exist at the
states' discretion. Such programs include, for example, groundwater
protection standards and monitoring; wellhead protection and
underground injection control programs under SDWA; controls over
facilities that treat, store, and dispose of hazardous waste under
the Resource Conservation and Recovery Act; statewide septic system
and pesticide management regulations; well abandonment standards; and
controls over chemical discharges from industrial and municipal
wastewater treatment plants under the Clean Water Act. Other
programs are targeted at more diffuse, or "nonpoint," sources of
pollution, such as agricultural and urban runoff.
OBJECTIVES, SCOPE, AND
METHODOLOGY
---------------------------------------------------------- Chapter 1:6
At the request of Representatives J. Dennis Hastert and Bill Paxon
and former Representative Blanche Lambert-Lincoln, we reviewed the
quality of drinking water in community water systems and private
wells. In discussions with the requesters' offices, we agreed to
provide information in response to the following questions:
-- What is known about the quality of drinking water from community
water systems and private wells in six states?
-- What factors influence the quality of drinking water from
community water systems and private wells?
In conducting this review, we collected information from a wide
variety of sources, including EPA, the U.S. Geological Survey, the
U.S. Public Health Service's Centers for Disease Control and
Prevention (CDC), the U.S. Department of Agriculture, the Bureau of
the Census, selected states, and other relevant organizations. We
judgmentally selected six states for our review--California,
Illinois, Nebraska, New Hampshire, North Carolina, and Wisconsin.
These states were selected on the basis of several factors, including
(1) the amount of information available on private wells located in
the states as identified in interviews with knowledgeable officials,
(2) the number or percentage of households that obtain their drinking
water from private wells, and (3) the states' geographical location.
To answer the first question, we obtained data from EPA on
contaminants found in community water systems in the six states for
fiscal years 1993 through 1996. We identified and obtained data on
contaminants found in private wells through interviews with drinking
water officials responsible for overseeing private wells in each
state. We also identified and obtained water quality studies done by
researchers in academia, industry, or government who analyzed private
wells in any of the six states as well as other states. We
interviewed federal, state, and local agency officials to discuss the
testing data available on community water systems and private wells.
We used EPA's primary drinking water standards--the MCLs that EPA has
established to protect public health--as our criteria for assessing
water quality at private wells.
To answer the second question, we interviewed federal, state, and
local government officials; representatives from the National Ground
Water Association; representatives of the state well drillers'
association within each of the six states; and water quality experts
from academia. We reviewed the federal and state regulations for
community water systems. For private wells, we obtained state and
local regulations on the construction and location of wells, as well
as operating and licensing requirements for well drillers. We also
collected and reviewed public educational literature designed for
private well users.
We provided a draft of this report to EPA, CDC, and the six states
for their review. Specifically, we obtained comments from EPA
officials, including the Director of the Implementation and
Assistance Division of the Office of Ground Water and Drinking Water,
and CDC officials from the National Center for Environmental Health
and the National Center for Infectious Diseases. We also obtained
comments from representatives of the state agencies responsible for
overseeing drinking water quality. We responded to their comments
throughout the report and summarized their views in the executive
summary and chapter 2.
Our work was conducted from July 1996 through April 1997 in
accordance with generally accepted government auditing standards.
DATA ON TOTAL COLIFORM BACTERIA,
NITRATE, AND OTHER CONTAMINANTS AT
COMMUNITY SYSTEMS AND PRIVATE
WELLS
============================================================ Chapter 2
Much more is known about the quality of drinking water from community
water systems than from private wells because community water systems
are tested much more extensively. Under SDWA, community water
systems must routinely test their water for the presence of up to 72
contaminants.\8 Private wells are not subject to SDWA, and none of
the six states we reviewed requires any routine testing of operating
wells. Two of the six states and some local governments require
minimal testing at new private wells before they are put into
operation.
Extensive data from community water systems in the six states that we
reviewed showed that total coliform bacteria\9 were the most common
contamination problem. Between 3 and 6 percent of the community
systems operating in the six states between fiscal years 1993 and
1996 exceeded the MCL for total coliform bacteria.\10 Relatively few
community systems exceeded other MCLs. The next most frequently
exceeded standard was for combined radium, with fewer than 1 percent
of the systems exceeding that standard in any one year.\11
Most of the data that we found on the quality of private well water
are for total coliform bacteria and nitrate.\12 The data--which come
from a variety of states, including the six we reviewed in
detail--indicate that a high percentage of private wells were
contaminated with total coliform bacteria and a lower percentage
contained excessive nitrate concentrations.\13 For example, studies
have reported contamination with total coliform bacteria in 15 to 42
percent of the private wells tested and excessive nitrate
concentrations in 2 to 18 percent of the private wells. In contrast,
fewer than 1 percent of the private wells contained a particular
pesticide above acceptable levels, according to the studies we
identified. Data from CDC, EPA, and others suggest to us that
contamination rates at private wells are related to a number of
characteristics of the wells, including their age and type.
EPA and state officials indicated that contaminants such as
pesticides found in community water system wells may also be present
in nearby private wells that draw on the same groundwater, but
private well water is seldom tested for contaminants other than
bacteria and nitrate. The 1996 amendments to SDWA require EPA to
develop, by August 1998, regulations that will require that community
water system operators notify their customers of the amount of
contamination found in their drinking water. However, this
information will not be provided routinely to private well users who
may use the same source of groundwater as the community system.
--------------------
\8 EPA requires that community water systems have treatment
techniques in place to reduce the presence of nine additional
contaminants that are not economically or technologically feasible to
detect through testing. Additional monitoring may be required
together with the use of the treatment techniques.
\9 Total coliform bacteria are microscopic, generally harmless,
organisms that live in the intestinal tracts of warm-blooded animals.
According to EPA, the presence of total coliform bacteria indicates
the possible presence of fecal and disease-causing bacteria.
\10 The MCL for total coliform bacteria that community systems must
meet is based on the presence or absence of coliform bacteria in a
percentage of all samples taken each month. The number of samples
taken depends on the size of the population served. The MCL is
exceeded when systems that take fewer than 40 samples per month
detect total coliform bacteria in more than 1 sample or when systems
that take 40 or more samples detect the bacteria in more than 5
percent of the samples. The MCL is also exceeded if any fecal
coliform bacteria or E. coli are detected.
\11 Note that the community water systems' data in this report are
limited to violations of MCLs and do not include violations of
monitoring requirements. It is possible that monitoring violations
could obscure violations of water quality standards.
\12 The sources of nitrate in drinking water include fertilizers,
animal waste, the contents of septic tanks, and decaying plant
material. Nitrate levels below 3 parts per million are considered
background levels, and higher levels are considered to be caused by
human activity. EPA's MCL for nitrate in drinking water is 10 parts
per million. Infants are particularly susceptible to high nitrate
levels and may develop methemoglobinemia (also known as "blue baby
syndrome"), a potentially fatal condition that restricts the movement
of oxygen through the bloodstream.
\13 In this report, private wells are considered contaminated if
total coliform bacteria are present in any amount. Nitrate
concentrations of more than 10 parts per million are considered
excessive.
COMPARED WITH PRIVATE WELLS,
COMMUNITY SYSTEMS MUST COMPLY
WITH EXTENSIVE TESTING
REQUIREMENTS
---------------------------------------------------------- Chapter 2:1
All community water systems must test their water for contaminants
regulated by SDWA. The frequency of testing varies from one
contaminant to another and ranges from more than once a day to once
every 9 years. Other factors that affect the frequency of testing
include the size of the population served by the system, the source
of the water (groundwater versus surface water), and past test
results. In addition, states with primacy and approved waiver
programs may grant waivers that reduce the sampling frequency for a
specific contaminant on the basis of previous sampling results and/or
an assessment of the system's vulnerability to each specific
contaminant.\14 Community systems report their test results to the
states and must also notify their customers when MCLs are violated.
The notification may be through the local media, by mail, or by hand,
depending upon the nature and duration of the violation.
While community water systems must test for dozens of contaminants as
part of their normal operations, testing at private wells is much
more limited, and the data are not always available for review. None
of the six states we reviewed requires any routine testing of
operating wells.\15 Of these six states, two (Wisconsin and Illinois)
require only that newly constructed wells be tested for total
coliform bacteria before they are put into operation. Illinois also
requires, and Wisconsin recommends, that new wells be tested for
nitrate. According to state officials, while North Carolina does not
require any testing, 22 of its 87 local health boards have private
well inspection and oversight programs and may require testing for
total coliform bacteria at new wells.\16 Similarly, all 58 counties
in California have private well oversight and inspection programs and
some may require testing for bacteria at new wells. State officials
were not able to identify how many counties require testing.
According to state officials, some commercial mortgage lenders
require that private wells be tested as a condition of the loan
approval. They said that testing is typically limited to total
coliform bacteria and nitrate. Well owners may choose to have the
testing done by either a private or a public (state or county)
laboratory. Officials told us that test data generated by private
laboratories are not submitted to any public agency, and therefore
the information is not captured in any state database. Several of
the state laboratories in the six states conduct testing for these
real estate transfers and do maintain the results in a public
database. Federal agencies that provide mortgage insurance,
including the departments of Veterans Affairs and Housing and Urban
Development, also require testing as a condition of providing their
insurance. For example, the Department of Housing and Urban
Development, in consultation with EPA, developed a testing
requirement for total coliform bacteria, nitrate, lead, and other
contaminants of local concern.
For the most part, private wells are tested at the well owner's
discretion. As with the testing done as part of a real estate
transfer, this self-initiated testing may be done by a private or a
public laboratory. Consequently, the data may or may not be entered
into a public database. According to officials we spoke with,
private laboratories treat their data as confidential and do not make
them available for review. This policy limits the amount of
available data on the quality of private well water.
Although EPA, state drinking water officials, and industry groups
recommend annual testing for bacteria, few well owners follow this
advice. For example, EPA's 1984 National Statistical Assessment of
Rural Water Conditions reported that "bacteriological tests and
chemical (or physical) water tests by rural residents were not
common. Slightly more than one-third of all rural households with
individual systems had tested the water at least once, with
bacteriological tests being more frequent than chemical tests." Data
from a 1994 CDC survey of 5,520 private well users across a
nine-state region show that 44 percent of the respondents said that
their well had never been tested for contamination, 44 percent said
that it had, and 11 percent did not know.\17 Of those that knew that
their well had been tested and could say when the test had occurred,
39 percent said that it was prior to 1990.
In the course of testing water quality at the request of more than
32,000 well owners since 1985, the University of Wisconsin asked them
how recently they had tested their water. Only 9 percent of the
owners reported having had a test done within the last year. The
overall responses are summarized in table 2.1.
Table 2.1
Years Elapsed Since Last Water Test Was
Conducted for Private Well Owners
Participating in University of
Wisconsin's 1985-96 Testing Program
1- 2- 5- More
Time frame for most Less 2 5 10 than Not
recent water quality than 1 year year year 10 Neve know
test year s s s years r n
------------------------ ------ ---- ---- ---- ------ ---- ----
Percent of respondents 9 6 10 6 6 3 61
----------------------------------------------------------------------
Source: University of Wisconsin Cooperative Extension Service.
--------------------
\14 We reported on the states' participation in the waiver program in
November 1995 (Flexibility in the Safe Drinking Water Act,
GAO/RCED-96-12R). At that time, we reported that 42 states had begun
issuing monitoring waivers by 1995. Of the remaining eight states,
three had approved programs but had not issued any waivers at the
time of our survey and five were still developing their waiver
programs.
\15 In this section, we make an important distinction between newly
constructed wells, which have not yet been placed in operation, and
existing wells, which are in operation and may have been so for many
years.
\16 North Carolina has 87 local health boards that serve the state's
100 counties. Some health boards serve more than one county.
\17 We obtained data from CDC that it had gathered in its survey.
CDC's report entitled A Survey of the Presence of Contaminants in
Water From Private Wells in Nine Midwestern States, U.S. Public
Health Service, Centers for Disease Control and Prevention, is
currently under review at CDC. The states surveyed were Illinois,
Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South
Dakota, and Wisconsin.
BACTERIAL CONTAMINATION IS THE
MOST COMMON PROBLEM AT
COMMUNITY WATER SYSTEMS IN THE
SIX STATES
---------------------------------------------------------- Chapter 2:2
Data for the six states we reviewed show that the standard for total
coliform bacteria was the most frequently exceeded standard at
community water systems. The number of systems exceeding the
standard for total coliform bacteria from fiscal year 1993 through
fiscal year 1996 ranged from 577 to 1,035. This represented about 3
to 6 percent of the approximately 17,000 to 18,000 community water
systems operating in the six states at some point during these years.
The community water systems in the six states we reviewed exceeded
the MCLs for contaminants other than total coliform bacteria much
less often. The most commonly exceeded standards, other than the
standard for total coliform bacteria, were those for radiological
elements, nitrate, and the herbicide atrazine.\18 Fewer than 1
percent of the systems exceeded the standard for any one of these
contaminants in any particular year. While the systems that reported
violations varied in size and used both surface water and
groundwater, most served fewer than 3,301 people and most relied on
groundwater as their source.\19 Violations of the most commonly
exceeded standards in the six states are analyzed in table 2.2.
Table 2.2
Number and Percentage of Community Water
Systems in Six States With at Least One
Water Quality Violation in Fiscal Years
1993-96 for the Most Frequently Exceeded
Standards\a
Systems with at Systems with at Systems with at Systems with at
least one least one least one least one
violation of violation of violation of violation of
standard in FY standard in FY standard in FY standard in FY
1993 (No. = 1994 (No. = 1995 (No. = 1996 (No. =
17,976) 17,727) 17,580) 17,443)
------------------ ------------------ ------------------ ------------------
SDWA
contamina
nt No. Pct. No. Pct. No. Pct. No. Pct.
--------- -------- -------- -------- -------- -------- -------- -------- --------
Total 1,035 5.76 785 4.43 659 3.75 577 3.31
coliform
bacteria
Fecal 229 1.27 101 0.57 63 0.36 51 0.29
coliform
bacteria
and/or
E.
coli\b
Nitrate 72 0.40 58 0.33 52 0.30 51 0.29
Combined 147 0.82 130 0.73 121 0.69 116 0.67
radium
(radium
226 and/
or
radium
228)
Atrazine 10 0.06 28 0.16 34 0.19 15 0.09
Alpha 55 0.31 56 0.32 53 0.30 47 0.27
emitters,
excludin
g radon
and
uranium
=========================================================================================
Total for 1,303 7.25 1,047 5.91 906 5.15 774 4.44
all
contamin
ants\c
-----------------------------------------------------------------------------------------
Legend
No. = number
Pct. = percent
\a Both surface water and groundwater systems are combined.
\b Violations for fecal coliform bacteria and E. coli are a subset
of the violations for total coliform bacteria and represent more
acute health risks to consumers.
\c Will not equal the total number of systems included above for two
reasons: (1) a system may have a violation in several SDWA
contaminant categories and (2) the total includes violations of
standards for other contaminants not listed above.
Source: GAO's analysis of data from EPA.
--------------------
\18 Atrazine is an herbicide used to control grasses and broadleaf
weeds, primarily on corn and sorghum fields. It is known to cause
mammary gland cancer in laboratory animals, and EPA classifies it as
a possible human carcinogen.
\19 EPA categorizes community water systems as very small, small,
medium, large, and very large. Very small systems serve from 25 to
500 people, while small systems serve from 501 to 3,300 people. From
fiscal year 1993 through fiscal year 1996, 80 percent of the systems
with at least one water quality violation were very small or small.
During that same period, 87 percent of the systems with at least one
water quality violation used groundwater, while 13 percent used
surface water.
LIMITED TEST DATA ON PRIVATE
WELLS INDICATE FREQUENT
CONTAMINATION FROM BACTERIA AND
NITRATE
---------------------------------------------------------- Chapter 2:3
Available data on the quality of water from private wells are, for
the most part, limited to information on total coliform bacteria and
nitrate. Whereas data on community water systems are collected using
EPA's standardized methodology, the data on private wells come from a
variety of sources using various methodologies. Given that potential
limitation, the data generally indicate that a high percentage of
private wells were contaminated with total coliform bacteria at the
time they were tested. A smaller percentage of private wells were
contaminated with excessive concentrations of nitrate. For example,
CDC's 1994 survey of the geographic distribution of contamination in
private wells across a nine-state region found that over 41 percent
of the wells were contaminated with total coliform bacteria and over
13 percent contained excessive concentrations of nitrate. In
addition, the survey showed that 11 percent of the wells were
contaminated with E. coli bacteria, which present a more acute
health risk than total coliform bacteria. Data from one national and
one statewide study that both used statistically random sampling
techniques found total coliform bacteria contamination in 42 and 15
percent of the private wells tested, respectively. Other data from
studies that used random sampling techniques showed excessive nitrate
concentrations at 2 to 19 percent of the private wells tested. Data
gathered by CDC, EPA, and others also suggested that contamination
rates can be affected by characteristics of a well, such as its type,
depth, and age.
SPECIFIC STUDIES SHOW A HIGH
PERCENTAGE OF PRIVATE WELLS
WITH CONTAMINATION
-------------------------------------------------------- Chapter 2:3.1
Several studies have shown a high percentage of private wells
contaminated with total coliform bacteria and nitrate above
acceptable levels. One of the more recent and extensive efforts was
by CDC. In 1994, CDC and state agencies sampled wells in nine
states, including three of the six that we reviewed. The purpose of
the survey was to measure total coliform bacteria, E. coli, nitrate,
and the herbicide atrazine. The study was motivated, in part, by the
discovery that a high proportion of water samples from rural wells
were contaminated with total coliform bacteria and E. coli shortly
after the disastrous 1993 flooding of the Missouri and Mississippi
rivers. The survey was intended to show the geographic distribution
of microbiological and chemical contamination in water from these
wells.\20 In total, over 5,500 wells were sampled, including more
than 500 each in Illinois, Nebraska, and Wisconsin. The samples
included wells ranging in age from 1 to 200 years and wells of many
different construction types, including wells that would not meet the
states' current construction standards. The total coliform bacteria,
E. coli, and nitrate results for all nine states are shown in table
2.3. (The atrazine data are presented later in this chapter.)
Table 2.3
Results of CDC's Survey of the Presence
of Contaminants in Water From Private
Wells in Nine Midwestern States
Percentage
of wells
Percentage with
of wells nitrate
with total Percentage levels
coliform of wells above
detections with EPA's
State and number of wells sampled \a E. coli\b standard
---------------------------------- ---------- ---------- ----------
Illinois (540) 45.9 15.4 15.3
Nebraska (598) 37.3 2.5 14.7
Wisconsin (534) 22.8 2.6 6.6
Iowa (526) 58.6 20.5 20.6
Kansas (716) 48.7 16.3 24.3
Minnesota (718) 27.3 4.5 5.8
Missouri (632) 57.4 22.6 9.7
North Dakota (673) 35.5 8.2 13.5
South Dakota (583) 40.1 8.4 10.4
======================================================================
Total (5,520) 41.3 11.2 13.4
----------------------------------------------------------------------
\a CDC's survey procedure was to test one water sample per private
well and note the presence or absence of any total coliform bacteria.
\b Wells in CDC's survey were also tested for E. coli. EPA requires
community water systems that detect total coliform bacteria in any
water sample to test that sample for fecal coliform bacteria or E.
coli.
Source: CDC.
Other studies have also reported the incidence of contamination with
total coliform bacteria and nitrate. The scope and methodology of
these studies are described below, and their results are summarized
in table 2.4. (Note that these studies were also not limited to the
six states we reviewed.)
-- In 1991, the University of Nebraska published a study
statistically designed to estimate the population at risk of
ingesting contaminated water from rural private wells.\21 The
study gathered test results from 2,195 rural wells from all of
the state's 93 counties. The selection criteria for the wells
required that they be on property actively engaged in farming
and/or at least 6 acres in size. In 1996, the Nebraska
Department of Health and the University of Nebraska-Lincoln
published a follow-up study that reported on tests done at 1,808
of the original 2,195 private wells. The studies reported total
coliform bacteria in about 18 percent of the wells and excessive
nitrate concentrations in 17 to 19 percent of the wells.
-- In 1990, EPA issued the National Survey of Pesticides in
Drinking Water Wells (Phase I). One of the two objectives of
the study was to determine the frequency and concentration of
pesticides and nitrate in drinking water wells nationwide.
(This study included both community and private wells.) The
survey was designed to yield results that were statistically
representative of the nation's community and rural private
wells. The study estimated that excessive levels of nitrate
were in 2.4 percent of the rural private wells. (The pesticide
results are discussed later.)
-- In 1990, an herbicide-manufacturing company presented to EPA the
results of its National Alachlor Well Water Survey, which
included testing for nitrate. The study sampled 1,430 rural
domestic wells in counties that used alachlor in 1986.\22 As
such, it is representative of the universe of private, rural
domestic wells in counties where the herbicide was sold. The
study reported excessive nitrate levels in 4.9 percent of the
wells. (The data on alachlor are presented later.)
-- In 1984, EPA issued the National Statistical Assessment of Rural
Water Conditions. The sampling, done in 1978 and 1979, covered
400 counties. Testing for water quality was done at 2,654
households that used either private wells, "intermediate
systems" (systems with 2 to 14 service connections), or
community water systems. This study reported total coliform
bacteria in 42 percent of the private wells and excessive
nitrate in 4.1 percent.
Table 2.4
Summary of Total Coliform and Nitrate
Results from Other Studies Using
Statistically Representative
Methodologies
Percentage of
samples testing Percentage of
positive for total samples exceeding
Study's name and date coliform bacteria MCL for nitrate
------------------------------ ------------------ ------------------
Nebraska Department of Health/ 18 in 1991 study 17.4 in 1991
University of Nebraska, 1991/ 15.1 in 1996 study
1996\ study\a 18.4 in 1996
study\b
EPA National Survey of Not tested 2.4
Pesticides in Drinking Water
Wells, 1990
National Alachlor Well Water Not tested 4.9
Survey, 1990
EPA National Statistical 42.1 percent 4.1
Assessment of Rural Water
Conditions, 1984
----------------------------------------------------------------------
\a The 1996 results are for 1,805 of the 2,195 wells tested in 1991.
\b The 1996 results are for 1,633 of the 2,195 wells tested in 1991.
In addition to the data described above, data that are not
statistically representative of conditions in a particular state also
exist. These data are generally consistent with the results just
described and are presented in appendix II. The two primary reasons
why these data may not be representative are that (1) the tests were
done at the request of well owners, who may have had the test done
because they suspected problems, or (2) the tests were done at new
wells that might have become contaminated with total coliform
bacteria during construction and would have had to be disinfected
before being put into operation. Some of the results are also from
specific studies that did not use statistically valid sampling
techniques.
--------------------
\20 While CDC's sampling strategy was designed to show the geographic
distribution of water conditions, it was not designed so that
estimates could be made about contaminated wells as a percentage of
the total universe of private wells in a particular state or in the
nine-state area. The testing was done at wells near the
intersections of a 10-mile grid overlaid on a map of each of the nine
states.
\21 Assessment of Statewide Groundwater Quality Data From Domestic
Wells in Rural Nebraska (Lincoln, Neb.: University of Nebraska
Press, 1991).
\22 Alachlor is an herbicide used on corn, soybeans, and peanuts.
EPA classifies it as a probable human carcinogen.
DATA SUGGEST THAT
CONTAMINATION RATES ARE
AFFECTED BY CHARACTERISTICS
OF WELLS
-------------------------------------------------------- Chapter 2:3.2
EPA, CDC, and others have also gathered data on private wells by
type, age, and depth. These data suggest that higher contamination
rates are associated with certain well construction characteristics.
The most common well types, which are described in more detail in
appendix I, are known as drilled, driven, bored, and dug. In its
1984 assessment of rural water conditions, EPA concluded that
"households served by dug and bored wells, wells in which the
water leaves the casing above ground level, wells with
inadequate covers, inadequately maintained wells, and shallow
wells all tended to have high coliform levels more commonly than
those served by wells without those characteristics."
According to data gathered by CDC, bored and dug wells had the
highest proportion of contamination. The material used to construct
the well casing is related to the well type and appears to affect
contamination rates. CDC's data showed that the brick and concrete
tile casings characteristic of dug and bored wells had higher
contamination rates than the steel casings characteristic of drilled
and driven wells. Other water quality researchers who have analyzed
data in Nebraska, Iowa, Kansas, and Ohio have also concluded that the
incidence of nitrate contamination is higher in wells with
open-jointed casing (i.e., brick or concrete tile) than continuous
casing (i.e., plastic or steel).
Researchers investigating the incidence of contamination do not all
emphasize the significance of the same well construction
characteristics, however. For example, a study of private wells in
Iowa concluded that "by far the most significant factor explaining
water-quality variations is well depth,"\23 while a study of nitrate
contamination in wells in Kansas emphasized the age of the well.\24
In a statement that applies to both the age and the type of well,
water quality scientists from the University of Nebraska concluded
that evidence supports
"the widely held belief that modern well construction practices
provide an effective barrier to surface contamination and can
reduce the incidence of nitrate contamination in domestic rural
wells."\25
Other factors that can influence water quality are discussed in
chapter 3.
--------------------
\23 The Iowa State-Wide Rural Well-Water Survey, Iowa Department of
Natural Resources (Nov. 1990).
\24 J. Steichen et al., "Contamination of Farmstead Wells by
Pesticides, Volatile Organics, and Inorganic Chemicals in Kansas,"
Ground Water Monitoring Review (Summer 1988).
\25 R.F. Spalding and M.E. Exner, "Occurrence of Nitrate in
Groundwater--A Review," Journal of Environmental Quality, Vol. 22
(July-Sept. 1993).
DATA ON PRIVATE WELLS FOR OTHER
CONTAMINANTS ARE VERY LIMITED
AND SHOW LOW RATES OF EXCESSIVE
CONTAMINATION
---------------------------------------------------------- Chapter 2:4
Limited data have been collected in the six states and elsewhere on
contaminants such as pesticides, heavy metals, and volatile organic
compounds in drinking water from private wells. State and local
governments do not require testing for these contaminants, and
states' databases show that well owners rarely request such testing.
The bulk of the data for these contaminants is collected through
specialized studies by government, industry, or academia. In
general, the incidence of these contaminants at concentrations above
their MCLs is on the order of 0 to 2 percent. The following studies,
not all of which used statistically random sampling techniques,
provide examples.
-- The University of Nebraska and the Nebraska Department of Health
issued a report in 1996 that described pesticide data collected
for two studies from 1985 through 1989 and during 1994 and 1995.
The first study tested water at 2,195 private wells, and the
second tested water at a subset of 1,808 of the original wells.
The wells were all on property that was actively being farmed
and/or at least 6 acres in size, and the studies were
representative of drinking water conditions under those
circumstances. Atrazine has been the most frequently detected
pesticide in Nebraska. Atrazine was detected at concentrations
above EPA's MCL in 1.0 percent of the private wells tested in
the first study and 2.6 percent in the second study. (All of
these later cases were accounted for by 2 of the state's 13
groundwater regions.)
-- In the 1994 effort described above, CDC also gathered data on
atrazine contamination in 4,847 wells across eight of the nine
midwestern states surveyed. Of the wells sampled, the
percentage with atrazine above the MCL ranged from 0.0 percent
to 0.6 percent for the eight states, with an aggregate
percentage of 0.2.
-- The 1990 National Alachlor Well Water Survey, sponsored by the
herbicide manufacturer and representative of rural private wells
in counties that used alachlor, estimated that 0.02 percent of
the rural private wells in those states had concentrations above
the MCL. The study also estimated that 0.1 percent had atrazine
concentrations above the MCL. EPA's representative 1990
National Survey of Pesticides in Drinking Water Wells estimated
that 0.6 percent of all rural private wells were contaminated
with a pesticide at a level over its MCL or Lifetime Health
Advisory Level. The same study estimated that 0.8 percent of
community water systems were contaminated with a pesticide at
concentrations above these levels.
-- Wisconsin's Department of Agriculture, Trade, and Consumer
Protection tested for atrazine in a sample representative of
private wells at dairy farms in 1988. Fewer than 1 percent of
the wells had concentrations above the state's enforcement
standard (which is the same as EPA's MCL). In another Wisconsin
Department of Agriculture project, the state distributed
atrazine testing kits to 2,187 people statewide. This
unrepresentative study showed that samples from 1 percent of the
wells tested exceeded the state's enforcement standard.
-- The Heidelberg College Water Quality Laboratory has also tested
for pesticides in thousands of midwestern private wells whose
owners have volunteered for testing since 1987. Although this
is not a representative sample, the results show that samples
from 1.1 percent of the wells exceeded the MCL for alachlor and
that samples from 0.1 percent exceeded the MCL for atrazine.
CONTAMINATED GROUNDWATER MAY
AFFECT BOTH COMMUNITY WATER
SYSTEMS AND PRIVATE WELLS
---------------------------------------------------------- Chapter 2:5
According to EPA and state drinking water officials, testing at
community water systems that detects contaminated groundwater may
indicate that water in nearby private wells is also contaminated. If
a private well and a community system both obtain their water from
groundwater that is contaminated, both may be affected. This is more
likely for contaminants that persist in the environment and migrate
through the soil to the groundwater. These include nitrate, some
pesticides, and volatile organic compounds. EPA also noted that
naturally occurring contaminants in groundwater, such as radiological
compounds, may affect both community and private drinking water
wells. In contrast, the presence of total coliform bacteria is
likely to be localized to a particular well because they are not
especially long-lived or able to travel far through the groundwater.
While it is difficult to generalize about the contamination levels
that community water system users and private well users face when
both obtain water from a contaminated aquifer, there is reason to
believe that the users of private wells may face higher exposure
levels. First, many community systems treat their water to remove
pollutants. The treatment is intended to remove some percentage of
the contamination from the source water. In contrast, most private
well users do not treat their water, particularly not using a method
capable of removing pesticides or organic compounds. Second,
community water wells are typically deeper than private wells.
Because contamination from human activity usually originates near the
surface and then disperses vertically and horizontally,
concentrations of contamination are likely to diminish with the
distance from the source and depth. Therefore, a shallow private
well is likely to tap into contaminated water before a deeper
community well does.\26
--------------------
\26 There are possible exceptions to this. One is that the flow of
contaminated groundwater from the pollution source may be away from a
private well and toward a community well. The reverse, of course,
could also be true. Another possible exception concerns contaminants
known as light, nonaqueous-phase liquids, such as benzene and
petroleum products, that "float" on groundwater--in contrast to
dense, nonaqueous-phase liquids that sink and collect toward the
bottom of an aquifer.
SDWA'S REQUIREMENT FOR EXPANDED
PUBLIC NOTIFICATION COULD
BENEFIT PRIVATE WELL USERS
---------------------------------------------------------- Chapter 2:6
SDWA requires that owners and operators of community water systems
notify their customers when treated water exceeds the MCL for a
particular contaminant. The 1996 amendments to SDWA require EPA to
strengthen the regulations for this requirement. In addition, EPA
must develop, by August 1998, regulations that will require more
comprehensive public notification about contaminated drinking water.
The owners and operators of community water systems will be required
to prepare annual reports that provide their customers with data on
all detections of regulated contaminants, regardless of whether the
detections exceed the MCLs.
While only a very small percentage of community water systems violate
the MCL for any contaminant other than total coliform bacteria, a
substantially larger percentage of systems do find and, if necessary,
remove some amounts of other contaminants. The Congress, in
reauthorizing SDWA, indicated that it was important for the customers
of community water systems to know about the levels of contaminants
in the water they consume. Because private well users who are
consuming untreated water from the same source may be exposed to even
higher levels of contamination, this information is likely to be of
interest to them as well, but there is now no requirement to notify
them.
CONCLUSIONS
---------------------------------------------------------- Chapter 2:7
Drinking water is vulnerable to contamination, and users that do not
have access to complete information about their water cannot be
certain that it is safe. Because private wells are not as
extensively regulated as community water systems and because private
well owners do not generally conduct frequent or comprehensive tests
of their water, they do not have complete information about its
safety.
This does not imply that private well users are all at risk or that
they should begin to test their water for all of the contaminants
regulated by community water systems. That would be unnecessarily
expensive. What it does suggest is that when there is information
already available from community systems that could alert private
well users to possible local contamination problems, these users
could benefit from that information. For example, community water
systems could provide a copy of their annual water quality report to
state and/or local public health agencies, which could then alert
private well users to localized contamination problems and advise
them to consider having their well tested for specific pollutants, if
appropriate. The agencies could publicize the availability of the
annual report through the local media, making sure that the notice
alerts private well users to the report's potential relevance to
their water supply. With the information from the annual report,
private well users can make informed choices about testing or
maintenance. Without the information, they may not be aware of
potentially harmful contamination.
RECOMMENDATION
---------------------------------------------------------- Chapter 2:8
To help ensure that private well users are better informed of
potential contamination problems and associated health risks, we
recommend that the Administrator, Environmental Protection Agency,
explore options that would provide such well users with information
on how to learn more about the quality of their drinking water and
the steps they can take to protect their drinking water source from
contamination. For example, state and/or local health agencies could
use the local media to alert private well users to consider testing
their water whenever the testing of a groundwater-supplied community
water system detects contamination that could potentially be present
in the same geologic formation supplying nearby private wells.
AGENCY COMMENTS
---------------------------------------------------------- Chapter 2:9
EPA officials commented that this report will prove useful in
educating the public on the threats to private drinking water wells.
EPA also noted that it sees its role in protecting the public health
as including private well users and providing them with helpful
information about drinking water. The agency, therefore, supported
the intent of our recommendation but suggested that it give EPA and
the states more flexibility and discretion in deciding how to ensure
that private well users are better informed about their water
quality. EPA also suggested that there is a need for general public
outreach to educate consumers on the need for periodic testing of
private drinking water wells. We have made revisions to reflect
EPA's comments.
CDC also agreed with the intent of the recommendation. The agency
commented that the data presented in this report could support
additional recommendations. Specifically, CDC pointed to gaps in
knowledge that could be filled by the routine testing of wells and
centralized collection of the test results. CDC also suggested that
reductions in the factors that influence contamination could be
achieved through the use of construction standards, maintenance,
inspections, and controls on land use and siting. We agree that
routine testing and centralized data collection would help fill the
gaps in knowledge about the quality of water from private wells and
that steps could be taken to reduce the factors that contribute to
water contamination. However, we do not include such recommendations
because the authority to require them rests with the states rather
than with EPA.
CDC also commented that this report does not emphasize the water
quality problems of small community water systems and that it
compares the quality of private well water only to that of large
community systems. Our report discusses data on the compliance of
community water systems of all sizes. It also points out that about
85 percent of the community systems are small and that 80 percent of
the systems with at least one MCL violation between fiscal years 1993
and 1996 were small or very small. Furthermore, in chapter 3, we
refer to a 1994 GAO report that discusses the technical and financial
difficulties of small systems in meeting the requirements of the
drinking water program.
The state representatives generally agreed with the intent of our
recommendation. However, several of the states expressed concern
that implementing the recommendation might place a large burden on
community water systems. In light of these comments and those from
EPA, we have revised the recommendation to provide flexibility in how
water quality information is made available to private well users.
The state representatives also provided other technical
clarifications and suggestions, which we incorporated as appropriate.
SEVERAL FACTORS INFLUENCE THE
QUALITY OF DRINKING WATER FROM
COMMUNITY WATER SYSTEMS AND
PRIVATE WELLS
============================================================ Chapter 3
The quality of drinking water supplied by community water systems and
private wells can be influenced by a variety of factors. First, the
quality of the source from which drinking water is extracted can have
a major influence in the quality of water at the tap, particularly if
the water is not treated in any way. Construction standards and
other controls are designed to ensure that new water systems and
private wells are properly constructed and protected from potential
sources of contamination. The extent of such controls and how well
they are implemented can also influence water quality. Finally, once
a new drinking water source--whether a community system or a private
well--is constructed, the extent of ongoing oversight and maintenance
activities can help determine whether the water will continue to be
safe. Activities such as periodic testing and inspections can
prevent minor problems from becoming major ones and thus minimize
problems that could adversely affect the quality of drinking water.
THE CONDITION OF THE SOURCE
INFLUENCES DRINKING WATER
QUALITY
---------------------------------------------------------- Chapter 3:1
Depending on the extent of treatment, the quality of the water
sources used to supply community water systems and private wells can
be a key factor in the quality of drinking water delivered at the
tap. Both groundwater and surface water are vulnerable to
contamination from human activities and naturally occurring
substances. When a water source is contaminated, some form of
treatment may be needed to ensure that the water is safe to drink.
However, community water systems are much more likely to treat their
water than private well owners.
According to EPA's recent survey of community water systems,\27 81
percent of the systems reported providing some type of treatment for
some or all of the water delivered to consumers. Some of the
reported treatment, such as water softening and iron and manganese
removal, is intended to improve the aesthetic quality of drinking
water while other types of reported treatment, such as disinfection
and the removal of organic chemicals, may be necessary for compliance
with EPA's health-based quality standards, or MCLs. More
significantly, community water systems are required to take
corrective action--by treating water or taking other
measures--whenever water quality testing detects contamination in
excess of the MCLs. Detecting and treating contamination at private
wells is generally done at the discretion of individual well owners.
Limited data are available on the extent to which private well owners
treat their drinking water. The Water Quality Association, an
industry group representing manufacturers and vendors of home water
treatment devices, does not collect data on sales to private well
owners. According to the association's executive director, however,
most of the treatment devices sold to the public are water softeners
that improve the aesthetic quality of water by removing hardness,
iron, and manganese. In addition, the state officials we interviewed
believe that well owners rarely treat their water except to improve
its aesthetic quality. However, in the shallower levels of the
aquifers tapped by private wells, untreated groundwater may contain
contaminants such as nitrate and pesticides that can pose health
risks.
--------------------
\27 During 1995 and 1996, EPA surveyed a statistically representative
sample of community water systems to collect information on their
operational and financial characteristics. See Community Water
System Survey (EPA-815-R-97-001a and EPA-815-R-97-001b, Jan. 1997).
CONSTRUCTION STANDARDS, SITING
REQUIREMENTS, AND OTHER
CONTROLS HELP REDUCE POTENTIAL
FOR CONTAMINATION
---------------------------------------------------------- Chapter 3:2
State construction standards and siting requirements play a key role
in determining the quality of drinking water at the tap and, for
private wells and community systems that rely on groundwater sources,
protecting the aquifer from contamination. All six of the states we
visited have established construction standards and siting
requirements for community water systems and private wells. However,
we found that while these states have a fairly rigorous approval and
inspection process for community systems, there is less oversight of
new private wells and less assurance that these wells comply with
state requirements.
NEW COMMUNITY SYSTEMS ARE
SUBJECT TO APPROVAL AND
CONSTRUCTION REQUIREMENTS
-------------------------------------------------------- Chapter 3:2.1
In keeping with their status as regulated public water suppliers,
community systems must go through a rigorous approval process. As a
condition of obtaining primacy under EPA's safe drinking water
program, a state must have a process for ensuring that all new or
substantially modified public water system facilities will be capable
of complying with applicable drinking water regulations. The six
states we visited require that detailed plans and specifications for
a new or substantially modified community system be prepared and/or
approved by a professional engineer. To ensure that such a system is
constructed according to the approved plans, the states conduct
inspections during construction or, when construction is complete,
require a certification from an engineer hired by the system that it
was constructed as approved. For new groundwater wells at community
systems, some states, such as Nebraska and New Hampshire, require
that test wells be drilled to ensure that the water will meet SDWA's
standards. Once the final well has been constructed, the states
generally require additional water quality testing before the new
system can be brought on line.
According to a recent EPA survey of drinking water infrastructure
needs,\28 community water systems must make significant investments
in improvements to their water sources and their treatment, storage,
and water distribution facilities if they are to continue providing
water that is safe to drink. EPA estimates that these systems'
infrastructure needs will total $138.4 billion over the next 20
years, including $76.8 billion needed now to meet SDWA's requirements
and protect public health. Many of the identified needs are related
to meeting current or future drinking water quality standards or
replacing facilities that have met the end of their useful lives and
are deteriorating. Furthermore, according to EPA, many small water
systems were improperly designed and constructed in the first place.
EPA's report states that "many small systems were built without
review of plans and specifications and were not required to adhere to
minimum design and construction standards." Officials in five of the
six states we visited generally agreed with EPA's conclusions,
particularly for older systems that were constructed before state
approval and construction requirements were in place. A Wisconsin
official told us that although some systems in the state may fit
EPA's description, they are exceptions.
State construction standards for community systems include criteria
for siting new facilities so that they are not located close to
potential sources of contamination. All of the states we visited
have established minimum distances, called setback requirements,
between a well and specific sources of contamination, such as
landfills and sewage lagoons. Community water systems may also take
steps to protect a larger area around their water source. In
general, this means identifying potential sources of contamination
within a designated area and adopting various controls, such as
zoning or land-use ordinances, to manage existing sources of
contamination and prevent new sources from locating within the
protected area. Depending on the source of their water, community
systems may protect the area around their groundwater well (wellhead
protection) or their surface water intake.
We did not obtain comprehensive information on the extent to which
community systems in the six states are participating in source water
protection programs. However, we learned that California does not
have an approved wellhead protection program\29 and that in several
other states, the approved programs are voluntary for most water
systems. In New Hampshire, for example, all new community water
systems are required to have wellhead protection programs, but for
existing systems, participation is voluntary. Some states allow
their water systems to qualify for reduced monitoring for some
contaminants as an incentive to participate in the protection
program. According to EPA's January 1997 survey of community water
systems, over one-third of all community water systems participate in
some type of effort to protect source water, such as adopting land
use or zoning controls and educating the public on the impact of land
use.
--------------------
\28 EPA Drinking Water Infrastructure Needs Survey: First Report to
Congress, EPA Office of Water (EPA 812-R-97-001, Jan. 1997).
\29 A few local communities in the state have received grants
directly from EPA to implement wellhead protection, but, according to
California officials, the state is not involved.
STATES' CONSTRUCTION
STANDARDS FOR NEW PRIVATE
WELLS AND EFFORTS TO ENSURE
COMPLIANCE VARY
-------------------------------------------------------- Chapter 3:2.2
All six of the states we visited have construction standards for
private wells. These standards generally specify appropriate
materials and construction techniques for various types of wells and
establish criteria for siting wells and for ensuring that they are
protected from contamination. In most instances, the states'
construction codes are the minimum statewide standards; state and
local regulators may establish more stringent requirements if
warranted by site-specific geologic or hydrologic conditions.
Officials in all six states generally agree that as long as an
aquifer is not contaminated, private wells that are (1) constructed
in accordance with current standards and (2) located an adequate
distance from potential contamination sources will provide
good-quality drinking water. However, we found that the states vary
in their efforts to ensure that construction and siting requirements
are met.
According to the National Ground Water Association, CDC, and state
drinking water officials, two of the most important elements of well
construction for ensuring good-quality drinking water are (1)
requirements for sealing or grouting the well to prevent
contamination from entering the groundwater\30 and (2) criteria for
siting the well, including requirements for minimum setback distances
between the well and potential contamination sources. We found that
these elements vary widely from state to state. For example,
Nebraska requires that the annular space (see ftn. 30) be sealed to
a minimum depth of 10 feet while in Wisconsin, the minimum ranges
from 0 (no grouting required) to 40 feet, depending on the drilling
method and the geological conditions. In New Hampshire, well
drillers are responsible for ensuring that each well is sealed
adequately for its particular location; the state does not specify
any minimum requirement for the depth of the seal. According to an
official of the California Department of Water Resources, which is
responsible for promulgating well construction standards, the state
is proposing to increase its requirements for sealing the annular
space in private wells from a depth of 20 feet to the 50-foot depth
required for community water systems. Both Illinois and Nebraska are
considering an increase in their requirements because state officials
believe that the current requirements may not be sufficiently
protective.
Similarly, the minimum setback distances between a private well and
various contamination sources also vary among the states we visited.
For example, the required setback distance from animal enclosures
ranges from 20 feet in New Hampshire to 100 feet in California and
North Carolina. The distance required between a well and a septic
tank ranges from 25 feet in Wisconsin to 100 feet in California and
North Carolina.\31
Officials from both California and Wisconsin told us that the setback
requirements for a private well are not necessarily based on an
assessment of what distance would be safe. According to an official
from the Wisconsin Department of Natural Resources, the minimum
distance required between a private well and a septic tank or other
potential source of contamination is simply a matter of "what will
fit on an average lot."
During our visits to the six states, we also obtained information on
various controls that are intended to ensure that newly constructed
private wells provide safe drinking water, meet state standards, and
are constructed by qualified individuals. We found differences in
several areas:
-- Permit requirements for new wells. Of the six states we
visited, only California and Illinois require water well
contractors to obtain permits for new wells prior to
construction. For the most part, the permits are issued by
county health departments. In Illinois, the permit application
must contain a plan and drawing of the proposed construction,
including the lot's size; the location of property lines and the
distances from the proposed well to septic tanks, abandoned
wells, and other sources of contamination; the type of well to
be constructed; and the driller's license number. Permit
applications may be denied if the available information
indicates that groundwater at the proposed site is contaminated.
Nebraska is implementing a permitting program; most of the
state's 23 natural resource districts\32 have established
groundwater management districts that will be responsible for
issuing permits for new wells. In North Carolina, the
permitting requirement is limited to the 22 (out of 87) local
health boards that have programs for overseeing private wells.
Four of the 72 counties in Wisconsin are authorized to issue
permits, and New Hampshire does not require permits for new
wells.
-- Registration of new wells. All six states require well drillers
to prepare a drillers' log or "well completion report" on each
new well. These reports contain information on the type and
depth of the well, the site, the materials used in construction,
and other information. The reports could be useful in helping
the state to develop an inventory of private wells, but we found
that some states question the accuracy of the reporting. For
example, North Carolina officials estimate that they are
notified of about 60 percent of all new wells through the well
completion reports, and in Nebraska, where well owners are
responsible for filing the drillers' reports with the state, an
estimated 40 to 60 percent of new wells are reported.
California officials raised questions about the reliability of
these reports; they said that reports from some drillers are
"suspiciously similar."
-- Water quality testing at new wells. Only two of the six states
we visited require water quality testing at newly constructed
wells, and the testing is limited to one or two contaminants.
Both Illinois and Wisconsin require testing for total coliform
bacteria, and Illinois also requires that new wells be tested
for nitrate. Some counties in California and North Carolina
require testing at new wells, generally for bacteria.
-- Inspection of new wells. Of the six states we visited, only
California and Illinois require the inspection of new private
wells to ensure that they are built in accordance with state
standards. In California, under the state's model well
ordinance, counties must inspect all new wells to ensure that
the annular space is properly sealed and that potentially
contaminated surface water or shallow subsurface water is thus
prevented from flowing into the well along the outside of the
well casing. The counties may also make an initial inspection
of the proposed drilling site, inspect the completed well, and
conduct other inspections as appropriate. State officials told
us that enforcement of the state's well construction standards
varies from county to county. Illinois also requires the
inspection of all new wells--either by the state or an approved
local agency--to determine whether construction and siting
requirements have been met. In North Carolina, 22 of the
state's 87 local health boards are authorized to inspect new
wells, but state officials were not sure about the extent to
which inspections were actually conducted. New Hampshire
officials told us that they do not have the resources to inspect
new wells, and neither Nebraska nor Wisconsin has an inspection
program for new wells.\33
-- Licensing of water well contractors. According to the chief of
Nebraska's water well standards program, the first line of
defense in avoiding well construction problems is the water well
contractor. With the exception of North Carolina, the states we
visited all have programs to license well drillers and pump
installers. North Carolina officials told us that anyone who
can pay the $50 fee can register as a well driller regardless of
his/her experience or technical proficiency. However, a
proposal for licensing water well contractors is before the
state legislature; under this proposal, well drillers and pump
installers would have to pass a written exam and a skills test.
The state well drillers' association supports the licensing
proposal.\34
-- Public education programs. A variety of state and local
organizations--including public health, environmental
protection, and agriculture agencies and the well-drilling
industry--are involved in efforts to educate consumers about
drinking water and groundwater protection. For example, both
EPA and the states have published information pamphlets that
advise well owners of the importance of locating wells away from
septic tanks and other sources of contamination and avoiding the
use or storage of dangerous chemicals near the wellhead. In
addition, several of the states we visited participate in a
program known as Farm*A*Syst, which is designed to provide
farmers and rural homeowners with the tools they need to
identify pollution risks on their property, including risks to
their private wells. The Farm*A*Syst program has been jointly
sponsored by the U.S. Department of Agriculture and EPA since
1991. Some state and local agencies, such as county extension
services, offer free water quality testing to private well
owners.
--------------------
\30 Many wells are constructed in a manner that creates a space
between the larger borehole and the well casing. Unless this area,
called the annular space, is properly sealed with cement or other
grouting material, contaminants may enter the groundwater through
runoff from the ground's surface. In addition, properly sealing the
annular space may prevent contamination from a shallow aquifer
infiltrating a deeper one.
\31 North Carolina will approve a setback of 50 feet between a well
and a cesspool or septic tank if a lot is not large enough for a
100-foot setback.
\32 Nebraska has established 23 natural resource districts to protect
and manage natural resources at the local level.
\33 In Wisconsin, 4 of the state's 72 counties have programs to
inspect new well construction.
\34 According to data filed in support of North Carolina's proposal
to establish a licensing program for well drillers, 15 states,
including North Carolina, do not have a licensing and certification
program for well drillers and pump installers.
ONGOING OVERSIGHT AND
MAINTENANCE HELP ENSURE THAT
EXISTING SOURCES OF DRINKING
WATER CONTINUE TO PROVIDE
GOOD-QUALITY WATER
---------------------------------------------------------- Chapter 3:3
While the proper construction and siting of community water systems
and private wells may be the most important safeguards against
contaminated drinking water, ongoing oversight is also necessary to
ensure that water continues to be safe. Community water systems are
subject to periodic testing, maintenance, and inspection
requirements. States are responsible for overseeing community water
systems to ensure that they meet the requirements and to take
corrective action when problems are identified. For private wells,
however, the primary responsibility for routine monitoring and
maintenance rests with individual homeowners. For the most part,
states play a minimal role in the oversight of existing private
wells.
COMMUNITY SYSTEMS ARE
SUBJECT TO PERIODIC TESTING
AND INSPECTION REQUIREMENTS
-------------------------------------------------------- Chapter 3:3.1
Community water systems are subject to extensive requirements for
testing water quality. In addition to periodic testing, community
systems must undergo comprehensive inspections, called sanitary
surveys, performed by state or county inspectors. According to EPA's
guidance, sanitary surveys should entail a detailed review of all
aspects of a water system's design, operation, and maintenance,
including an inspection of the water source, treatment and storage
facilities, and distribution system. In addition, a sanitary survey
can provide regulators with an opportunity to establish a "field
presence" with the owners and operators of water systems and to
educate them about proper monitoring and sampling procedures, as well
as any changes in regulations. States see sanitary surveys as one of
the most important tools they can use to help ensure the capability
of water systems to deliver safe drinking water. The six states we
visited had a policy of inspecting their community water systems at
least once every 2 to 5 years.
When problems are identified through water quality testing or
sanitary surveys, federal and state regulations require community
water systems to correct these problems. For example, if periodic
testing discloses contamination in excess of allowable levels, water
systems must treat the water or take other steps, such as finding a
new water source or consolidating with a neighboring system, to
comply with water quality standards. If the systems fail to come
into compliance, they are subject to enforcement action by the states
or EPA. Sanitary surveys also detect some serious problems with a
direct impact on water quality, but more often, they identify less
significant operational or maintenance deficiencies that, if left
unaddressed, could become major problems. Timely corrective action
helps ensure that drinking water will continue to be safe.
Despite these safeguards, we have previously reported concerns about
several aspects of EPA's safe drinking water program and how it is
being implemented by states and community water systems. On the
basis of a nationwide questionnaire and a review of 200 sanitary
surveys in four states (Illinois, Montana, New Hampshire, and
Tennessee), we reported in 1993 that sanitary surveys were often
deficient in how they are conducted, documented, and/or interpreted
and that deficiencies disclosed in the surveys frequently went
uncorrected.\35 In 1994, we reported that small community water
systems, which comprise about 85 percent of all community systems,
often lack the technical or financial capability to meet the
requirements of the drinking water program.\36 We found that the lack
of reliable cost and performance data on affordable alternative
technologies, inadequate authority to address nonviable water
systems, state resource constraints, and other barriers have impeded
efforts to help bring the systems into compliance. We also reported
that as the requirements for the drinking water program expanded
after the 1986 amendments to SDWA, states lacked the resources to
fully implement key oversight and quality assurance activities, such
as conducting sanitary surveys and providing technical assistance to
small water systems.\37
With the passage of the 1996 amendments to SDWA, the Congress has
slowed the pace of regulation and provided significant new funding
for state oversight programs and loans for capital improvements to
community water systems. In addition, the 1996 amendments require
EPA to identify technologies for small water systems that are
affordable and feasible for achieving compliance with MCLs and
establish other programs and requirements designed to improve the
capacity of small water systems to meet SDWA's requirements.
--------------------
\35 Drinking Water: Key Quality Assurance Program Is Flawed and
Underfunded (GAO/RCED-93-97, Apr. 9, 1993).
\36 Drinking Water: Stronger Efforts Essential for Small Communities
to Comply With Standards (GAO/RCED-94-40, Mar. 9, 1994).
\37 See Drinking Water: Widening Gap Between Needs and Available
Resources (GAO/RCED-92-184, July 6, 1992) and Drinking Water Program:
States Face Increased Difficulties in Meeting Basic Requirements
(GAO/RCED-93-144, June 25, 1993).
WELL OWNERS ARE RESPONSIBLE
FOR ONGOING OVERSIGHT AND
MAINTENANCE OF EXISTING
PRIVATE WELLS BUT OFTEN ARE
UNAWARE OF THEIR IMPORTANCE
-------------------------------------------------------- Chapter 3:3.2
Private well owners are responsible for ensuring that their wells
continue to provide good-quality drinking water. None of the six
states we visited requires periodic water quality testing or conducts
routine inspections at existing private wells. Most testing at
existing private wells is done at the discretion of the well owners
or when required by lending institutions at real estate transfers.
Although Wisconsin does not have a formal program for inspecting or
monitoring existing wells, the state will test the quality of water
from wells located in areas "at risk" for pesticides or volatile
organic compounds. Similarly, North Carolina is conducting free
nitrate testing in private wells located near intensive livestock
operations. (See app. II for the results of tests in 1995-96.)
Although none of the states we visited conducts routine inspections
of private wells, some state or county agencies will inspect wells at
the request of individual well owners. For example, Nebraska offers
a technical assistance program to private well owners and will
inspect the condition of the well and look for potential sources of
contamination. North Carolina also conducts inspections in response
to consumers' complaints; the state receives more than 700 complaints
each year from home or business owners because of problems with their
wells or pumps. State officials told us that inspectors invariably
find that the problems are due to improper well construction or pump
installation.\38 New Hampshire does not have the resources to inspect
new or existing wells; state officials told us that they have
conducted only four or five inspections over the past 12 years,
generally in response to consumers' complaints. According to a New
Hampshire official, the state licensing board for water and well pump
contractors hears several consumer complaints each year. Improperly
constructed wells must be repaired or replaced by the licensed
contractor.
Despite various efforts to educate consumers about these issues,
officials in several states believe that many homeowners are not
aware of the need to regularly inspect their wells to check for signs
of deterioration, identify needed maintenance, and ensure that the
wells are protected from contamination. The importance of routine
oversight and maintenance of existing wells is evident from the
results of CDC's survey of private wells in nine midwestern states.
The survey identified a strong correlation between high rates of
contamination and older, shallower wells. Many of the wells in which
bacterial or nitrate contamination was detected showed evidence of
deterioration or faulty construction, such as cracked well casings,
which would have been revealed by routine inspections.
Data obtained in CDC's survey indicate that many of the 5,520 wells
would not meet current construction standards. For example, 2,051
(or 37 percent) of the wells had one or more openings--including
holes or cracks in the well casing, openings between the lid and the
casing, and faulty seals around the electric line inlet in the well
cap--through which contamination could easily enter the well.\39
CDC's survey also found that of the 1,873 wells with a vent to allow
air into the well, 655 (35 percent) did not have the vent properly
screened to keep out animals and insects. While improper well
construction does not guarantee poor-quality drinking water, it does
increase the risk of contamination and the importance of periodic
testing and inspection.
States vary in the extent of their authority to enforce well
construction standards and regulate the well drillers responsible for
implementing them. For example, several states have the authority to
suspend or revoke the license of a water well contractor who violates
well construction standards. In contrast to other states, North
Carolina does not license well drillers, and state officials told us
that the state has very little enforcement authority over well
drillers. If the state or a county finds a well that was not
properly constructed, the well driller is given 30 days to correct
the problem or is subject to monetary penalties. Corrective action
can include abandonment of the well.
Even where adequate enforcement authority exists, its use depends on
whether states or local agencies become aware of problems and are
willing to deal with them.\40 Neither Nebraska nor New Hampshire
inspects new wells, and inspections are limited to certain counties
in North Carolina and Wisconsin. An official from California's
Department of Water Resources, citing the potential conflict between
enforcing well construction standards and promoting development, said
that enforcement of the standards varies from county to county.
--------------------
\38 Prior to about 15 years ago, North Carolina conducted random
inspections of new and existing private wells, focusing on well
drillers suspected of performing inadequate work. However, the state
no longer has the resources to conduct random inspections.
\39 For another 1,216 wells included in the survey (22 percent), the
applicable questions were left blank or the surveyors were unsure
about the existence of improper openings.
\40 We did not collect information on the extent to which the states
used their enforcement authority to force well drillers to correct
identified problems or to suspend or revoke well drillers' licenses.
DESCRIPTION OF COMMON WELL
CONSTRUCTION METHODS
=========================================================== Appendix I
Many types of wells are currently in use, including some that are
technologically obsolete. The following is a brief description of
the most common well construction methods:
-- Drilled well. This is the most common type of private well. It
is constructed by either a cable tool or a rotary method,
usually to depths of 50 feet or more, with a diameter of 4 to 6
inches. It may have the capacity to provide water for
households, industry, irrigation, and community systems.
-- Driven well. These wells are generally shallow and typically
have a small diameter of 1.5 to 3 inches. They are constructed
without the aid of any drilling or boring device. Instead, a
series of threaded pipes are driven into the ground with a heavy
weight. Driven wells are feasible where the water table is
shallow and the ground is a permeable sandy soil.
-- Bored well. These wells are typically 10 to 100 feet deep, 8 to
36 inches in diameter, and built with hand-operated or
power-driven augers.
-- Dug well. These are shallow, large-diameter wells constructed
by excavating with power machinery or hand tools instead of
drilling or driving. The sides of the well may be supported by
brick, fieldstone, or wood, rather than steel piping. Dug wells
are the most "old fashioned" of the well types, as well as the
most vulnerable to contamination, because contaminated surface
water can easily enter the top of the well or contaminated
shallow groundwater can seep through the sides.
DATA ON CONTAMINATION BY TOTAL
COLIFORM BACTERIA AND NITRATE AT
PRIVATE WELLS
========================================================== Appendix II
Table II.1
Data on Contamination by Total Coliform
Bacteria at Private Wells
Data collection process
----------------------------
Location, Percentage of
approximate wells with total Owner'
number of coliform Nonrandom New s
samples, and contamination selection wells\ reques
Source of data date and date process\a b t\c
------------------------ --------------- ---------------- ------------ ------ ------
Illinois Department of Illinois, 32.2 in 1994
Public Health 9,500 in 1994, 33.3 in 1995 X X
9,200 in 1995
North Carolina State North Carolina, 24.9 in 1995 X
Laboratory of Public 23,000 in 24.0 in 1996 X
Health 1995,
22,000 in
1996\d
University of Wisconsin Wisconsin, 14 during 1985- X
Cooperative Extension 27,700 during 96
1985-96
Iowa State-Wide Rural Iowa, 686 sites 44.6 during X
Well-Water Survey during 1988-89 1988-89
-----------------------------------------------------------------------------------------
\a The wells tested for this survey were not selected using a
statistically randomized design.
\b The state data contain an unknown proportion of results from tests
at newly constructed wells. These states require that new wells be
disinfected before being put into service. Therefore, contamination
at these wells may have been eliminated before they were put into
service.
\c Data generated from tests requested by well owners may not be
representative if well owners test because they suspect a problem.
\d Based on 11 months of sampling.
Table II.2
Data on Contamination by Nitrate at
Private Wells
Data collection
process
----------------------
Percentage of
Location, wells with nitrate
approximate number above EPA's Nonrandom Owner's
of samples, and standard of 10 selection request\
Source of data date ppm\a process\b c
------------------------ ------------------- ------------------ ------------ --------
Illinois Department of Illinois, 10.3 in 1994 X
Public Health 6,000 in 1994, 10.0 in 1995
6,200 in 1995
Wisconsin Cooperative Wisconsin, 10.2 during X
Extension Service 27,000 during 1985-96
1985-96
Wisconsin Department of Wisconsin, 4,300, 17.9 X
Natural Resources since 1988
North Carolina North Carolina, 948 9.4 in 1995-96\d X X
Department of wells adjacent to
Environment, Health, and intensive livestock
Natural Resources operations, 1995-
96
North Carolina Statewide North Carolina, 3.2 in 1989-90 X
Nitrate Survey 9,000 in 1989-90
Water Quality Ohio, Illinois, 3.4 during X
Laboratory, Heidelberg Indiana, Kentucky, 1987-95
College, Ohio and West Virginia,
35,000 during
1987-94
Iowa State-Wide Rural Iowa, 686 sites 18.3 during X
Well-Water Survey during 1988-89 1988-89
Kansas Farmstead Well Kansas, 103 during 28.2 during X
Contamination Survey 1985-86 1985-86
-----------------------------------------------------------------------------------------
\a Parts per million.
\b The wells tested for this survey were not selected using a
statistically randomized design.
\c Data generated from tests requested by well owners may not be
representative if well owners test because they suspect a problem.
\d In this study, North Carolina reported the percentage of private
wells with nitrate concentrations above 9.5 parts per million.
MAJOR CONTRIBUTORS TO THIS REPORT
========================================================= Appendix III
RESOURCES, COMMUNITY, AND
ECONOMIC DEVELOPMENT DIVISION
------------------------------------------------------- Appendix III:1
Luther Atkins, Assistant Director
Ellen Crocker, Evaluator-in-Charge
Ross Campbell, Evaluator
Karen Keegan, Attorney
Gerald Laudermilk, Evaluator
Stephen Licari, Evaluator
Allan Rogers, Assistant Director
*** End of document. ***