How often should you test well water?
Short answer: Test a private well at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH, according to the EPA and CDC. Test right away after flooding, well repairs, nearby land changes or a change in taste, color or smell, and test more often if someone is pregnant or a child lives with you.
The baseline: once a year
The EPA says to test your private well annually for total coliform bacteria, nitrates, total dissolved solids and pH. [source] The CDC gives the same yearly list and adds that you should check your well every spring for mechanical problems. [source] The Virginia Department of Health says testing once a year is a good idea. [source]
Test right away when…
- you're told about well water problems in your area, or there are known groundwater problems nearby
- conditions near the well change: flooding, land disturbance, new construction, industry or waste disposal sites
- you replace or repair any part of the well system
- the water's taste, color or smell changes [source] [source]
- you or someone you live with becomes pregnant, or a child starts living with you [source]
More often for vulnerable households
The EPA says you may want to test more often if small children or elderly adults live in the home, or someone is pregnant or nursing. [source]
What states add
| Source | Frequency advice |
|---|---|
| New York State Dept. of Health | Bacteria at least yearly; other contaminants every 3–5 years [source] |
| Hunterdon County (NJ) Dept. of Health | Yearly for bacteria; nitrate, arsenic and VOCs every five years [source] |
| Penn State AASL | Coliform yearly; pH and total dissolved solids every three years [source] |
| New Jersey PWTA (landlords) | At least once every five years for rental properties [source] |
FAQ
How often should I test my well water?
Test a private well at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH, according to the EPA and CDC. Test right away after flooding, well repairs, nearby land changes or a change in taste, color or smell, and test more often if someone is pregnant or a child lives with you.
Should I test my well after a flood?
Yes. The EPA and CDC both say to test right away when flooding or other changes happen near your well.
Do I need to test more often if I'm pregnant?
The CDC says to test when you or someone you live with becomes pregnant, and the EPA says households with pregnant or nursing people may want to test more often.
Sources
- US EPA – Protect Your Home's Water (accessed 2026-10-23)
- CDC – Guidelines for Testing Well Water (accessed 2026-10-23)
- Virginia Department of Health – Private Well Water Information (accessed 2026-10-23)
- NYSDOH – Private Wells (accessed 2026-10-21)
- Hunterdon County – Well and Septic Care Guide (PDF) (accessed 2026-10-23)
- Penn State AASL – Drinking Water Testing (fees) (accessed 2026-10-23)
- NJDEP – N.J.A.C. 7:9E PWTA rule (courtesy copy) (accessed 2026-10-21)
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