About this data

Well Water Nerd summarizes public records of private well water tests. It does not test wells, and nothing here is a measurement of your water.

What the numbers are

Every figure on a town, county or state page is computed from a named public source: state summaries of homeowner tests, individual samples from federal and state monitoring, state well construction records, and state lists of regulated sites. Each page cites its sources with retrieval dates, and the method notes on each page say how non-detects, suppressed values and combined figures are handled.

What they cannot tell you

• Whether your well is safe. Two wells a few hundred feet apart can differ many times over. Only a certified laboratory test of your own tap answers that.
• Whether an area is representative. People test more often when they suspect a problem, and agencies sample near known contamination. Pages flag targeted sampling where it applies.
• Current conditions. Summaries cover the years shown on each page; some sources end years ago.

Health information

Health summaries describe what regulators and public health agencies have published about each contaminant. They are general information, not medical advice. If you are pregnant, have an infant, or have a health condition affected by drinking water, talk to your doctor and test your well.

Limits

Where a page says EPA limit, it means the federal maximum contaminant level or action level. Where it says state guidance level, it means the level the state uses for private wells, which for several contaminants is stricter than the federal one. Both are stated with each table.

Corrections

If a number looks wrong, write to [email protected] with the page and the figure. Every value can be traced to its source record.