How often should you test your well water? (New York)

As of 2026-10-07. From US EPA and the New York State Department of Health (NYSDOH). Private wells aren't regulated like public water, so testing is up to the owner. Sources are linked below.

The short answer

Who says	What to test	How often
NYSDOH (Test Your Well)	E. coli and coliform bacteria	Each year
NYSDOH (Test Your Well)	Lead; nitrate and nitrite; arsenic	Every 3-5 years
US EPA	Total coliform bacteria, nitrates, total dissolved solids and pH	Every year

NYSDOH: "Test your water at the tap at least once a year for bacteria and every 3-5 years for the other contaminants listed to the right." EPA: "Test your private well annually for total coliform bacteria, nitrates, total dissolved solids, and pH levels. If you suspect the presence of other contaminants, you should test for those also."

When in the year

NYSDOH: "The best time to test your water is in the late spring or early summer." Its coliform page explains why: "coliform contamination is most likely to show up during wet weather." It also says a single sample is only a snapshot of your well's water quality, so more samples give more confidence.

When to test sooner or more often

EPA says you "should also test your private well immediately if":

"There are known problems with ground water or drinking water in your area"
"You replace or repair any part of your well system."
"You notice a change in your water quality (i.e. odor, color, taste)."
Conditions near your well have changed significantly, such as new construction or land disturbance.

EPA adds: "You may want to test more frequently if small children or elderly adults live in your house or if someone in your house is pregnant or nursing." NYSDOH: "If you have experienced bacteria problems in the past, it is recommended that you test your well more frequently."

Where to test

Use a NYSDOH ELAP-certified lab (find one). NYSDOH says "Your lab will provide instructions and bottles." For what testing costs, see published lab prices. If a bacteria test comes back positive, see next steps.

Got your results back? The NY guide explains about two dozen common tests, with a fill-in worksheet.

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Instant download. 14-day no-questions refund. Printable guide (PDF), New York Edition 1.0.

Sources

NYSDOH, Test Your Well: Protect Your Family's Water (Pub. 6628, revised June 2025)
NYSDOH, Coliform Bacteria in Drinking Water Supplies
US EPA, Protect Your Home's Water (updated 2026-02-26)