How Often Should You Test Your Well Water?
Testing frequency depends on the contaminant and your situation. This guide gives a practical schedule for annual, periodic, and event-driven testing.
Quick Answer
Test your private well at least once a year for total coliform bacteria, E. coli, nitrate, and pH, and whenever something changes. Test less-frequent items like arsenic, lead, and other metals periodically. Because private wells are generally not federally regulated, this routine is entirely up to you.
A practical testing schedule
| Test | How often |
|---|---|
| Total coliform and E. coli | At least once a year |
| Nitrate | At least once a year, more often with a pregnancy or infant |
| pH | Annually, with routine checks |
| Arsenic, lead, metals, radon, uranium | Periodically, and based on local risk |
| Full comprehensive panel | Every few years or on any major change |
Test again after these events
- Flooding or heavy runoff near the wellhead
- Any repair or service on the well, pump, or plumbing
- A change in taste, color, odor, or clarity
- A nearby spill, new septic system, or land-use change
- Illness in the household that could be waterborne
- Buying a home with a private well, before you rely on it
Events can override the calendar
Your state or county health department may recommend additional local tests, for example if arsenic, uranium, or radon are common in your area. A state-certified laboratory can help you build a schedule that fits your geology and household.
Frequently asked questions
- What is the single most important test to do every year?
- Bacteria (total coliform and E. coli) is the top annual priority because contamination can happen quickly and cannot be detected by look, taste, or smell. Nitrate is a close second, especially with infants or pregnancy.
Sources & references
- Well Testing — CDC, accessed October 29, 2026
- Protect Your Home’s Water: Private Wells — US EPA, accessed October 29, 2026
This guide is documentary research and general information, not a laboratory analysis or professional assessment of your specific well. See our disclaimer.