Drinking Water

Glass being filled with water

About 90% of people in the United States get their water from a community water system. The U.S. Environmental Protection Agency (EPA) sets regulations for treating and monitoring drinking water delivered by community water systems. Drinking water protection programs at the state and national levels play a critical role in ensuring high-quality drinking water and in protecting the public’s health.

We Track That

The Tracking Network has data and information about the levels of several contaminants that can be found in drinking water. These contaminants were selected for the Tracking Network because they occur more frequently in drinking water at levels that may be of public health significance.

The drinking water data used in the Tracking Network are gathered as part of the water quality monitoring requirements set out by the U.S. Environmental Protection Agency (EPA) and state agencies. Tracking Network data are the only set of consistent drinking water quality data nationwide. While they are not gathered specifically to assess the level of exposure or to track changes in water quality over time, they can be used to determine the potential for public health impacts from contaminant levels of concern.

The main issues considered in the development of the contaminant-specific measures presented on the Tracking Network included the following:

  • Exposure patterns
  • Monitoring requirements/sampling frequency
  • Censored values
  • Drinking water quality standards/Maximum Contaminant Levels (MCLs)

Types of Data

The indicators for drinking water describe public water use and the levels of various contaminants in public water supplies. These data indicate the potential for public health effects from contaminant levels of concern.

Public Water Use
This indicator shows the number of community water systems per state and the number of people receiving water from those community water systems. The data is gathered from state grant recipients and can be used to estimate the population potentially exposed to contaminants in community water systems.

Drinking Water Contaminants
Data for these measures come from state grant recipients. For each contaminant, you can determine the following:

  • Distribution of level of contaminant in finished drinking water
    These data show the number of community water systems and their concentrations of contaminants. You can use these data to see how well the community water systems are producing high-quality water.
  • Potential for exposure to the contaminant in finished drinking water
    These data show estimates of the number of people served by community water systems along with the concentration of contaminants. You can use these data to determine the potential for a population’s exposure to contaminants in community drinking water
  • Level of contaminant in finished drinking water
    These data show quarterly and yearly average concentrations of a contaminant in finished drinking water. You can use these data to estimate potential long-term exposure to contaminants in drinking water.

Unregulated Drinking Water Contaminants
These measures provide information to the public on the water systems where PFAS chemicals and perchlorate were detected, and where the two chemicals with the EPA health advisory (PFOA and PFOS) were found in exceedance of that level. The measures also provide information on the water systems where samples were taken and no chemicals were detected.

Perchlorate can disrupt the normal function of the thyroid gland in both children and adults. The maximum contaminant level for perchlorate is 56 ug/L.

Data Highlight
Map of Tracking Network's Data Explorer tool showing point map of community water systems

View point-level community water system data using Tracking Network’s data explorer tool.

Data in Action

Making sure that drinking water remains in compliance with recommended standards is the most important way to prevent health problems caused by contaminants in drinking water. Protecting water sources, providing effective and reliable water treatment, and monitoring water quality are the main strategies for providing high-quality drinking water.

Read these success stories to learn about the drinking water related work happening in our funded Tracking Programs.

California | Iowa | New Mexico | Vermont | Wisconsin

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Explore Drinking Water Data
Data Explorer
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