Community Water System Service Area Boundaries

Community Water System Service Area Boundaries

The Safe Drinking Water Act (SDWA) defines a community water system as a public water system that has at least 15 service connections that serve year-round residents or that regularly serves at least 25 year-round residents.

The community water system service area boundary is the geographic area that receives drinking water from a given community water system. 

Why are Service Area Boundaries Important?

Understanding service area boundaries for a community water system helps connect water system details with information about the people drinking that water. Making this connection supports a variety of use cases as well as critical research to better protect public health and provide clean and affordable drinking water.

Use Cases

Accurate, comprehensive service area boundary data for community water systems across the U.S. can help to improve water decision-making at the federal, state, regional, and local levels. The EPA has compiled use cases that illustrate the variety of analyses and uses of service area boundary data. Most uses fall within one of the following categories:

• Informing public health and emergency response efforts to protect the public and critical infrastructure during emergencies. 
• Supporting environmental justice analyses. 
• Planning and affordability analyses of drinking water investments. 
• Information sharing that allows the public to determine where their drinking water comes from. 

Download the detailed list of use cases (pdf) (154 KB).

Browse the Map

EPA developed a national dataset that combines community water system service areas available from both published state sources supplemented with modeled boundaries. Browse the map on EPA’s GeoPlatform, download the data, and read more about the techniques EPA developed to create community water system service area boundaries below.

Scope

This dataset contains over 44,000 unique service areas for community water systems across all 50 states. While not 100% comprehensive, these systems cover 99% of the population served by community water systems. Over 40% of systems are sourced from 20 state databases. The remaining systems, those with no state supplied boundary, were modeled using machine learning techniques. This effort uses state sourced service areas to train a model on dozens of explanatory variables in order to approximate service areas where none were accessible. Note that EPA did not use all available state boundaries in certain cases where the quality could not be verified. EPA used its review of published state data (pdf) (1MB) to inform whether state supplied boundaries were of sufficient quality to include in the dataset or whether modelled boundaries would provide more accurate representations of the service area boundary.

Methods & Attributes

Each water system service area contains useful attribute information: critically, the system’s federal public water system ID (PWSID). The PWSID links the water provider to the federally reported system data located in the Safe Drinking Water Information System (SDWIS). The PWSID was linked to the service areas and used to populate basic information, such as, number of service connections, population served, and primary service area type (for example, mobile home park). Also note, this dataset can be used to couple violation data, which is publicly available on the SDWIS Federal Reports Search, with the geography a system serves. For example, Maximum Contaminate Level (MCL) violations, monitoring and reporting violations, and failure to complying with treatment technique violations.

This dataset used SDWIS data from submission year 2023 quarter 4 to establish the universe of community water systems. Going forward, the EPA plans to update this dataset to capture service area boundaries for more of the community water system universe and improve the current boundaries as better data becomes available.

Limitations

Because geographic areas can be served by multiple types of water systems that are not shown on the map – such as, private wells and non-community water systems – this tool should be used as a first step in learning more about the systems that serve your area. If you cannot identify a water system that serves you, it could be for the following reasons:

• You are on a private well, which EPA does not regulate. You can explore private well data in more detail by visiting the EPA developed nationwide map of private domestic wells.
• Your water comes from a non-community water system, which are not currently mapped. These systems are defined as:
  • Non-Transient Non-Community Water System: A public water system that regularly supplies water to at least 25 of the same people at least six months per year. Some examples are schools, factories, office buildings, and hospitals which have their own water systems.
  • Transient Non-Community Water System: A public water system that provides water in a place such as a gas station or campground where people do not remain for long periods of time.
  • Your water comes from a community water system that is not mapped due to model input limitations that did not produce reliable/accurate boundaries. For example, many tribal and territorial community water systems are not mapped for this reason.

If you have questions or would like to correct an error you see on the map, please contact us.

Services, Documentation, and Data

The national geospatial dataset of water system service area boundaries provided on this page is periodically updated by EPA.

EPA Resources

• EPA’s Community Water System Service Area Boundaries Data Standard (pdf) (349 KB) — For community water system service area boundary data, EPA has developed a set of national standards for data elements, terminology and definitions, and metadata with the goal of universal adoption among organizations generating or publishing service area boundaries. These standards will facilitate harmonization, use, and analysis.
• EPA’s Community Water System Service Area Boundaries Map — EPA developed a national dataset that combines service area boundaries available from both published state sources supplemented with modeled boundaries for systems with no state data or where the quality of state data could not be verified . Read more about the techniques EPA researchers used to delineate community water system service area boundaries in the available downloads and explore the community water system service areas on EPA’s mapping portal.
• State Service Area Boundary Dataset Summaries (pdf) (1MB) — In late 2023, EPA prepared summaries of publicly available community water system service area datasets from selected states. The state summaries were used to inform the National Data Standard and to aid EPA in assessing the quality of the available state data for inclusion in its national dataset.
• Use Cases for Community Public Water System Service Area Boundaries (pdf) (154 KB) — EPA compiled use cases that illustrate the variety of analyses and uses of service area boundary data.

Other Resources

• Environmental Policy Innovation Center’s (EPIC) Provisional Water Utility Service Area Boundaries — In 2022, the non-governmental organization, EPIC, along with collaborators SimpleLab and the Internet of Water Coalition, released a provisional national map of drinking water service area boundaries to support water and climate programs at the federal, state, and community levels. EPIC continues contribute to this initiative to improve the accuracy and use of these data.
• U.S. Geological Survey (USGS) National Dataset of Public-Supply Water Service Areas — USGS released a national dataset of public water service areas for the conterminous U.S. that delineates boundaries at the community or water system scale. The dataset, published in 2022, represents areas of active service between 2010 and 2020. USGS uses this data to better understand the U.S. public water supply use and identify where there may be challenges meeting water demands of sufficient quality.

Frequently Asked Questions

What are service area boundaries?

Service area boundaries describe the geographic area that receives drinking water from a given community water system.

What types of public water systems are included in EPA’s service area boundary dataset?

Currently, service area boundaries are only available for Community Water Systems. A community water system is a public water system that has at least 15 service connections that serve year-round residents or that regularly serves at least 25 year-round residents.

The current dataset contains over 44,000 unique service areas for community water systems across all 50 states. While not 100% comprehensive, these systems cover 99% of the population served by community water systems.

What are the benefits of having service area boundaries?

Understanding service area boundaries for a community water system helps connect water system details with information about the people drinking that water. Making this connection supports a variety of use cases as well as critical research to better protect public health and provide clean and affordable drinking water. Example use cases for service area boundaries include:

• Informing public health and emergency response efforts to protect the public and critical infrastructure during emergencies.
• Supporting environmental justice analyses.
• Planning and affordability analyses of drinking water investments.
• Information sharing that allows the public to determine where their drinking water comes from.

How were the service area boundaries developed?

The service area boundary dataset is comprised of both state supplied and modeled service area boundaries. Over 40% of systems are sourced from 20 state databases. The remaining systems, those with no state supplied boundary, were modeled using machine learning techniques. Note that EPA did not use all available state boundaries where the quality could not be verified. EPA used its review of published state data (pdf) (1MB) to inform whether state supplied boundaries were of sufficient quality to include in the dataset or whether modeled boundaries would provide more accurate representations of the service area boundary.

What are the limitations of this dataset?

Because geographic areas can be served by multiple types of water systems that are not shown on the map – such as, private wells and non-community water systems – this tool should be used as a first step in learning more about the systems that serve your area. If you cannot identify a water system that serves you, it could be for the following reasons:

• You are on a private well, which EPA does not regulate. You can explore private well data in more detail by visiting the EPA developed nationwide map of private domestic wells.
• Your water comes from a non-community water system, which are not currently mapped. These systems are defined as:
  • Non-Transient Non-Community Water System: A public water system that regularly supplies water to at least 25 of the same people at least six months per year. Some examples are schools, factories, office buildings, and hospitals which have their own water systems.
  • Transient Non-Community Water System: A public water system that provides water in a place such as a gas station or campground where people do not remain for long periods of time.
• Your water comes from a community water system that is not mapped due to model input limitations that did not produce reliable/accurate boundaries. For example, many tribal and territorial community water systems are not mapped for this reason.

Does EPA plan to update this dataset over time?

As new or improved service area boundary data are provided to EPA, this service area boundary dataset will be updated. EPA is currently exploring options to map non-community water systems as well.

I see an error in this dataset, who do I contact to correct it?

If you have questions or would like to correct an error you see on the map, please contact us.