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Private well water — what to test when EPA SDWIS doesn't cover you

If you're on a private well, EPA SDWIS shows nothing for your address — and that's not because the water is fine. It's because EPA's authority stops at public water systems. The well is yours.

Published 2026-04-25 · Last reviewed 2026-07-03 · methodology

Who's on a private well

About 13% of US households use private wells per the USGS Water Census. The share spikes in rural counties — over 50% in much of Appalachia, the Ozarks, northern New England, and parts of the rural Southwest.

If you're under any state-mandated 'Notice to Private Well Users' regime, you'll get reminders. If not — testing is on you.

Annual tests every well should get

Total coliform bacteria + E. coli — indicators of fecal contamination. Cheap (~$30 at most county health departments).

Nitrate — agricultural runoff signal; especially important if pregnant or formula-feeding infants. ~$25-50.

pH + total dissolved solids — corrosion + mineral indicators.

If your area has known issues: arsenic ($30), uranium ($35), radon-in-water ($30), VOCs ($150).

One-time / triennial tests

Lead — only if your home has lead service line, lead solder, or brass fixtures pre-1986. Test from kitchen tap after 6+ hours of stagnation.

Heavy metals panel — once at well drilling, once every 5-10 years. Includes mercury, cadmium, chromium, copper.

Pesticides + herbicides — only if you're agricultural-adjacent. ~$200 per panel.

Radioactivity (gross alpha + radium) — once at drilling, then if uranium or radon-in-water flags.

When to test more often

Visible water change (color, smell, taste) — test immediately for total coliform + nitrate.

Family illness suspected to be water-related — test coliform + E. coli + lead immediately.

Flood event in the area — test coliform within 2 weeks; pump + sanitize the well first.

Nearby fracking, mining, agricultural application — test arsenic + heavy metals + VOCs at least annually.

Selling the home — many states require a current well-water test as part of disclosure.

What zipradar shows

EPA SDWIS data for the dominant public utility serving the ZIP — but a clear flag where ZIP-level coverage shows 'mixed: public utility + private wells'.

Link to your state's well-water program (every state has one; quality varies wildly).

We never store private well-test results — those are your records, not ours.