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What is Source Water ?
Source water is untreated water from streams, rivers, lakes, or
underground aquifers which is used to supply private
wells and public drinking water.
Most public and some private well drinking water is treated
before it enters our homes. While some treatment is usually necessary,
the costs of treatment and risks to public health can be reduced
by ensuring that source water is protected from contamination.
Where Does Drinking Water Come
From?
Most source water is defined as surface or ground water. If you
live in a large metropolitan area, the majority of your drinking
water probably originates from a surface source such as a lake,
stream, river or reservoir. The land area that can have an impact
on these water bodies is called a aquifer
recharge area, and can be delineated on a map.
If you live in smaller community
or have a private well, it is more likely that your water originates
from underground and is pumped to the surface through a well. Ground
water comes from natural under ground layers, often of sand or gravel,
that contain water. These formations are called aquifers. The land
area that can have an impact on the quality of this underground
water is called the watershed.
Drinking water suppliers now provide reports (sometimes called
consumer confidence reports that explain
where drinking water comes from, and what contaminants may be in
it. You can also view information about
your watershed, groundwater supply, and drinking water supplier
in EPA's database.
Additional Information:
Where Does Drinking Water Come From?
Reliable Sources - General Information
What are the Threats to Source Water?
There are many contaminants that
may be present in source water before it is treated.
These include:
- Microbial contaminants, such as viruses and bacteria,
which may come from sewage treatment plants, septic systems, agricultural
livestock operations, and wildlife.
- Inorganic contaminants, such as salts and metals, which
can occure naturally or result from urban stormwater runoff, industrial
or domestic wastewater discharges, oil and gas production, mining,
or farming.
- Pesticides and herbicides, which may come from a variety
of sources such as agriculture, stormwater runoff, and residential
uses.
- Organic chemical contaminants, including synthetic and
volatile organic chemicals, which are by-products of industrial
processes and petroleum production, and can also come from gas
stations, urban stormwater runoff, and septic systems.
- Radioactive contaminants, which can be naturally occurring
or be the result of oil and gas production and mining activities.
Additional Information:
What contaminants may be found in drinking water?
List of the drinking water contaminants that
EPA regulates, including their sources in drinking water and their
potential health effects.
Contaminant Source Inventory
and Assessment Tools
Assessing the Risks
While many states, water systems, and localities have watershed
and wellhead programs , the 1996 Safe
Drinking Water Act Amendments placed a new focus on source water
quality. States have been given access to funding and required to
develop Source Water Assessment Programs (SWAP)
to assess the areas serving as public sources of drinking water
in order to identify potential threats and initiate protection efforts.
The source water assessment programs created by states differ since
they are tailored to each state’s water resources and drinking
water priorities. However, each assessment must include four major
elements:
- delineating (or mapping) the source water assessment area,
- conducting an inventory of potential sources of contamination
in the delineated area,
- determining the susceptibility of the water supply to those
contamination sources, and
- releasing the results of the determinations to the public.
These steps are described in more detail in the Source
Water Assessment section of this site. Our SWAP Contact
List has state specific contacts and links to State web sites.
Why Protect It?
Protection of drinking water at the source can be successful in
providing public health protection and reducing the treatment challenge
for public water suppliers. Source water quality can be threatened
by many everyday activities and land uses, ranging from industrial
wastes to the chemicals applied to suburban lawns. Private
well owners are urged to test regularly for common contaminants
such as microbes and nitrate-nitrogen. Water systems are heavily
regulated through the Public Water System
Supervision Program, and must respond to this threat to public
health with regular water quality monitoring and actions ranging
from well closure to expensive treatment. In some cases, source
water protection can eliminate or forestall the need to change or
modify treatment processes. Treatment is expensive and source water
protection can save consumers significant money.
The Source Water Protection section of
this site provides more information about protection programs.
EPA's Focus on Source Water Protection
The 1996 Safe Drinking Water Act Amendments
placed a new focus on source water protection:
States are to implement Source Water Assessment Programs (SWAPs)
to assess areas serving as sources of drinking water in order to
identify potential threats and initiate protection efforts.
Annual Water Quality Reports, produced
by water system operators, provide consumers with information about
their source water.
States can fund source water protection activities through the Safe
Drinking Water State Revolving Fund. Source water assessments
and protection measures are eligible uses of the Drinking Water
State Revolving Fund (DWSRF) set-asides. States may use the funds
for a mixture of source water related local
assistance activities. For example, funds are available
for Land Acquisition and Conservation
Easements, and Wellhead Protection
Programs.
The UIC Program works with Stateand local
goverrnments to oversee underground injection of waste in order
to prevent contamination of drinking water resources.
Drinking water protection approaches must be uniquely tailored to
each unique local situation. While most of these efforts will be
primarily utility, state and/or locally led, there are a variety
of Federal tools which can be used such as those available through
Clean Water Act and various agricultural programs. In addition,
there are a number of national organizations, such as American Water
Works Association, the National Rural Water Association, the National
Association of Counties and the Trust for Public Lands (to name
only a few) that are taking action in the source water protection
arena. One of EPA’s roles is to encourage partnerships and
provide information that can be used by those directly involved
in implementing source water protection. Please see our Annotated
Bibliography of Source Water Protection Materials.
Source Water Protection and Underground Storage Tanks: Partnership
Opportunity
The Offices of Ground Water and Drinking Water and Underground Storage
Tanks are working together to reduce the risks of underground storage
tanks to drinking water sources. In a July 20, 2004 joint memo to
Regional Water Division Directors and UST/LUST Directors, Cynthia
Dougherty and Cliff Rothenstein outlined recommended actions to
determine whether USTs are one of the risks to drinking water sources in
their Region, and to coordinate work to make the best use of resources
and increase public health protection.
Additional Information:
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