At a glance
We Track That
In the United States, 9 out of 10 people get their water from a community water system. The U.S. Environmental Protection Agency (EPA) sets regulations for treating and monitoring community drinking water. National and state drinking water protection programs play a critical role in ensuring high-quality drinking water and in protecting the public's health.
In contrast, about 1 in 8 Americans get their drinking water from a private well. Private well water quality is not regulated at the federal level and only a few laws in some states exist. Well owners are responsible for ensuring the water from the well is safe to drink. About 1 in 5 sampled private wells were contaminated with at least one chemical at levels that could affect health.
The public water data used in the Tracking Network are gathered as part of the water quality monitoring requirements set by the EPA and state agencies. The private well water data come from the U.S. Geological Survey. The well water indexes also incorporate data from the Federal Emergency Management Agency and CDC.
These data are not gathered specifically to assess level of exposure or to track changes in water quality over time. However, they can be used to determine the potential for public health impacts from contaminant levels of concern.
Several issues were considered in the development of the Tracking Network's drinking water contaminants measures. The main issues include the following.
- Exposure patterns
- Monitoring requirements/sampling frequency
- Censored values
- Drinking water quality standards/Maximum Contaminant Levels (MCL)
Types of Data
The indicators for drinking water describe public water and private well water use and quality in the United States.
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 comes from state grant recipients. It can be used to estimate the population potentially exposed to contaminants in community water systems.
The Tracking Network has data on regulated and unregulated contaminants in drinking water from community systems. They were selected because they occur more frequently in drinking water at levels that may be of public health significance
Regulated Drinking Water Contaminants
Data for these measures come from health departments funded by the Tracking Program. For each contaminant, you can determine the following.
- Distribution of level of contaminant in finished drinking water
- Potential for exposure to the contaminant in finished drinking water
- Level of contaminant in finished drinking water
Regulated Drinking Water Contaminants
- Arsenic
- Atrazine
- Di(2-ethylhexyl) Phthalate (DEHP)
- Disinfection By-products (DBP)
- Nitrate
- Tetrachloroethylene
- Radium
- Trichloroethylene
- Uranium
Unregulated Drinking Water Contaminants
These measures provide information on
- water systems where unregulated contaminants were detected.
- where PFOA and PFOS were in exceedance of EPA health advisory level.
- water systems where samples were taken but no chemicals were detected.
Unregulated Drinking Water Contaminants
The measures for this indicator include well water indexes (WWIs), populations dependent on well water, and well water contaminants. The WWIs identify and rank the potential impact of drought, flood, and wildfire on communities dependent on private well water.
Note: It is NOT appropriate to use the WWIs to characterize impact or contamination to individual private wells.
Access the Data
Use the Data Explorer to create custom maps, tables, and charts.
View data in simple Quick Reports.
Get machine-readable data from the Application Program Interface (API).