Learn where drinking water comes from, how it is treated and monitored, and how to interpret information about your own water. These guides can help you understand what reaches your tap—and what available water-quality data can and cannot tell you.
Where drinking water comes from
Surface water, groundwater, watersheds, wells, and public water supplies.
How drinking water is treated
What treatment plants do, why treatment varies, and what happens before water reaches the distribution system.
How water quality is monitored
Sampling, testing, regulatory monitoring, and what system-wide results can tell you.
Read your water-quality report
Consumer Confidence Reports, contaminants, limits, units, and how to interpret the numbers.
Explore local water data
Use public monitoring information to investigate water quality in your area.
When household testing makes sense
What home testing can answer, what it cannot, and how to choose an appropriate test.