Source Water Protection Basics

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What is source water?

Surface water (streams, rivers, and lakes) or ground water (aquiferHelpaquiferA natural underground layer, often of sand or gravel, that contains water.s) can serve as sources of drinking water, referred to as source water. Source water provides water for public drinking water supplies and private water wells. 

Public utilities treat most water used for public drinking water supplies. Protecting source water from contamination can reduce treatment costs. Protecting source water also reduces risks to public health from exposures to contaminated water.


Source water assessments

Source water assessments provide water utilities, community governments, and others with information needed to protect drinking water sources. The 1996 amendments to the Safe Drinking Water Act (SDWA) outline six steps for conducting source water assessments for public water systems (PWSs).  

Step 1 - Delineate the source water protection area (SWPA).

Delineation shows the area to be protected based on the area from which the PWS draws its drinking water supplies.

Step 2 – Inventory known and potential sources of contamination.

The contaminant source inventory lists all documented and potential contaminant sources or activities of concern that may be potential threats to drinking water supplies.

Step 3 – Determine the susceptibility of the PWS to contaminant sources or activities within the SWPA.

Determining susceptibility of the PWS to inventoried threats relates the nature and severity of the threat to the likelihood of source water contamination.

Source water protection programs rate the susceptibility of  public drinking water supplies to inventoried threats.Source water assessments rate the susceptibility of public drinking water supplies to inventoried contamination threats.

Step 4 – Notify the public about threats identified in the contaminant source inventory and what they mean to the PWS.

Effective programs ensure that the public has information necessary to act to prevent contamination.  

Step 5 – Implement management measures to prevent, reduce, or eliminate risks to your drinking water supply.

The assessment information can support formulation and implementation of measures to protect the source water.  These measures can be tailored to address each threat or array of risks specific to each PWS.

Step 6 – Develop contingency planning strategies that address water supply contamination or service interruption emergencies.

Water supply replacement strategies are an indispensable part of any drinking water protection program in the event of short- or long-term water drinking water supply disruption.

Learn more about conducting source water assessments

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Roles in source water protection

 Protecting source water is everyone's responsibility. Everyone has a role, including:

  • EPA and other federal agencies
  • States
  • Local governments
  • Water utilities
  • Businesses and industries
  • Non-governmental organizations
  • Individuals

EPA provides information and encourages partnerships for source water protection planning. EPA's Safe Drinking Water Act (SDWA) and Clean Water Act (CWA) programs provide tools to protect source water. Additional protection tools can be found in other EPA programs and various agricultural programs.

State and local governments and water utilities play a critical role in protecting source water.  They are well positioned to help tailor protective actions to unique local situations. 

States completed source water assessments in 2002 for all public water systems.  States are now implementing strategies to help local communities use the information obtained from these assessments. States also may provide resources to help fund local protection activities, such as wellhead protection programs for ground water and watershed management programs for surface water.

Local governments can develop zoning requirements to ensure that businesses using hazardous materials are not located near water supplies. Localities can also protect source water areas by implementing land use controls such as acquisition or conservation easements.

Water utilities can promote source water protection to their communities.  Utilities can benefit when they educate and partner with others to protect their source waters.

Businesses and industries can take actions to protect drinking water sources, for example by:

  • Reducing their use of harmful contaminants
  • Ensure their wastes do not discharge into ground water or surface water

Non-governmental organizations can provide:

  • Funding 
  • Research

Individuals can take action, for example by:

  • Getting involved in local source water protection efforts
  • Reducing their use of pesticides around the home
  • Ensuring that their septic systems are property maintained

Proper septic system maintenance is particularly important for people who rely on private wells for their drinking water.

Learn more about what you can do in your community to protect sources of drinking water

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Funding source water protection

There is no single funding source for implementing source water protection activities. Two significant sources of potential funding from EPA programs are the Drinking Water State Revolving Fund (DWSRF) and the Clean Water Act State Revolving Fund (CWSRF).

Fortunately, broad-based funding can mean broad-based support for protection activities. Actions that protect sources of drinking water can help federal programs, states, and communities meet other environmental and social goals.

Learn more about funding opportunities for source water protection

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