How to Test Your Private Well Water
The EPA regulates public water systems, but private wells are the owner's responsibility — no one tests them for you. The modeled risk maps on this site tell you what's likely in your area; a test tells you what's actually in your water.
What to test for
- Every well, at least once: arsenic, nitrate, coliform bacteria, pH, and total dissolved solids.
- Annually: nitrate and coliform bacteria (these change with seasons and rainfall).
- If you have older plumbing: lead and copper.
- Near farms, industry, or airports/military bases: add pesticides and PFAS.
Two ways to test
Certified lab test (most accurate): your state or county health department often offers low-cost or free arsenic and nitrate testing — start there. A state-certified lab gives you numbers you can trust for choosing treatment.
At-home test kit (fast screening): a good first pass to see whether you have a problem before paying for a full lab panel.
If your health department doesn't offer testing, a mail-in certified lab kit is the middle path: lab-grade numbers for arsenic, nitrate, bacteria, metals and more, without hunting down a local lab.
Find out what's actually in your well
Private wells are not regulated by the EPA — nobody tests your well for you. Arsenic, nitrate and coliform bacteria are the three most common private-well problems, and none of them has a taste or smell. A certified lab test checks all of them at once; the CDC and EPA recommend testing every well at least once a year.
Basic screening only. Confirm arsenic, nitrate and bacteria with a certified lab.
Find a certified drinking-water labAmazon links are affiliate links — we may earn a commission at no extra cost to you.
After you test
Compare your results to the EPA limits: arsenic 10 µg/L, nitrate 10 mg/L, lead 15 µg/L (action level). If anything is over the limit, match a filter to the specific contaminant with our filter selector — arsenic and nitrate both require reverse osmosis.