Jump to main content.

Frequent Questions

Where does drinking water come from?

If you live in a large metropolitan area, most of your drinking water probably comes from a surface source such as a lake, stream, river, or reservoir. Sometimes these sources are close to the community, and sometimes they are many miles away.

If you live in a small community or in an isolated area, it's more likely that your water originates underground and is pumped to the surface through a well. Ground water comes from natural underground formations, often consisting of sand or gravel, that contain water. These formations are called aquifers.

If you own a private well, you're responsible for making sure that the water is safe to drink. Private wells are not regulated by EPA's drinking water standards.

What are the threats to source water?

Many contaminants might be present in source water before it's treated, including the following:

  • Microbial contaminants, such as viruses and bacteria, which can come from sewage treatment plants, septic systems, agricultural livestock operations and wildlife.
  • Inorganic contaminants, such as salts and metals, which can occur naturally or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming.
  • Pesticides and herbicides, which can 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 occur naturally or as the result of oil and gas production and mining activities.

Two publically available resources that may describe potential or actual threats to your water supply are source water assessments and consumer confidence reports. First, your water supply and state drinking water program should have an assessment of the source water protection area from which it draws water which identifies potential threats. This assessment includes:

  • Description of the source water protection area
  • Inventory of potential types of contamination, and
  • Evaluation of how susceptible the water system is to being contaminated by the activities or land uses in the inventory.
Community water supplies also provide reports, sometimes called consumer confidence reports or water quality reports, that explain where your drinking water comes from and what contaminants might be in it. These reports also tell consumers what contaminants have been detected in their drinking water and how these detection levels compare to drinking water. Contact your water supplier to get a copy of your report.

How does the Safe Drinking Water Act address source water protection?

The 1996 Amendments to the Safe Drinking Water Act provide a new approach for EPA and states. In addition to relying on standards and regulations that address water safety at the tap, measures are in place to ensure the quality of drinking water by protecting it from the source to the tap.

  • Every state now has an approved source water assessment program and has completed source water assessments for most public water system. Each assessment identifies the area of land that most directly contributes the raw water used for drinking water and evaluates the risk of contamination of the water system.


  • Drinking water suppliers now provide reports, called consumer confidence reports, that explain where your drinking water comes from and what contaminants might be in it.


  • EPA provides funding to states through the Drinking Water State Revolving Fund (DWSRF) for assessment and protection activities.

Drinking water protection approaches must be tailored to each unique local situation. Although most source water protection efforts are primarily utility, state, or locally led, a variety of federal tools can be used, such as those available through the Clean Water Act, Underground Injection Control Program, and various agricultural programs. In addition, a number of national non-governmental organizations, such as the American Water Works Association, the National Rural Water Association (NRWA), the National Association of Counties (NACo), and the Trust for Public Lands (TPL), are taking action in the realm of source water protection. One of EPA's roles is to encourage partnerships and provide information to those directly involved in source water protection.

What is a source water assessment?

A source water assessment is a study that defines the land area contributing water to each public water system, identifies the major potential sources of contamination that could affect the drinking water supply, and then determines how susceptible the public water supply is to this potential contamination. Public utilities and citizens can then use the publicly available study results to the take actions to reduce potential sources of contamination and protect drinking water. As required by the Safe Drinking Water Act, states have completed source water assessments for virtually every public water system.

What funding is available for source water protection?

There is no single source of funding for implementing source water protection plans and activities. A variety of programs can be a source of funding for source water protection activities at the local, state, and federal levels. States used funds available through the Drinking Water State Revolving Fund (DWSRF) to conduct state assessment programs and have the option to use a portion of their money for source water protection purposes such as land acquisition and wellhead head protection programs. Through the Clean Water State Revolving Fund (CWSRF), as of 2002, 30 states had funded non point source projects that are protecting drinking water, including purchase of land or easements, wetland protection and restoration, remediation of contamination from leaking underground storage tanks, agricultural best management practices for crop and small animal operations, and upgrading and replacement of failing onsite septic systems.

What can I do locally?

Click on this icon for a list of quick things you can do to protect source water
Click on this icon for a list of quick things you can do to protect source water
Your state, community, watershed association or public water supplier might have activities and programs in place or plans to protect drinking water sources. Here are more things you can do.
  • Citizen involvement includes suggested actions you can take individually and with your community
  • Local protection includes planning resources, management measures and strategies that can prevent source water contamination.
  • Where you live can be used to find EPA regional offices, location information, contact names and case studies.
  • Related links can be used to find state Web pages and other resources.

How can I learn more about source water protection?

Read the Citizen's Guide to Ground Water Protection and take the Source Water Protection Training, which includes an introduction to source water protection programs, describes best management practices, and provides information about the delineation of source water areas for water supplies.

Local Navigation

Jump to main content.