How to test a private well

Use a state-certified laboratory. Test every year. Add extra analytes based on where you live and what you see, smell, or taste — not based on a filter advertisement.

This page cites CDC (page dated 1 July 2024), EPA Protect Your Home’s Water (last updated 26 February 2026), and EPA Home Water Testing (EPA 816-F-05-013, May 2005). Retrieved 29 August 2026.

Why this is on you

CDC: EPA rules that protect public drinking water systems do not apply to privately owned wells. Government officials do not regulate, treat, or monitor tap water from private wells. EPA says the same: if you drink from a household well, you alone are responsible for assuring it is safe.

When to test more often

CDC and EPA both say to test immediately if:

• You are notified of well-water problems in your area
• Conditions near the well change (flooding, land disturbance, new construction or industry)
• You replace or repair any part of the well system
• Taste, color, or smell changes
• Someone in the household is pregnant, or a child starts living with you (CDC). EPA also flags small children, elderly adults, and nursing.

EPA also says you may want to test more often if small children or elderly adults live in the house. Source: EPA Protect Your Home’s Water (last updated 26 February 2026).

What the annual indicators mean

CDC: water-quality indicators such as coliforms, pH, and total dissolved solids are typically not harmful themselves. They indicate that water may be contaminated with something else.

• Total coliforms. If the count is high, harmful germs may also be present. You can also test for fecal coliforms or E. coli. A positive fecal coliform or E. coli result likely means feces have entered the well. CDC notes that an indicator E. coli test does not show whether dangerous types of E. coli are present.
• Nitrates. CDC: all well owners should test for nitrates at least once a year. High levels can make people sick, especially babies. Sources include animal waste, septic systems, fertilizers, and farm runoff.
• pH. Too low or too high can damage pipes. Heavy metals such as lead can then leak into the water.
• Total dissolved solids. How much “stuff” is dissolved. Higher levels are more likely to leave scale on pipes and devices.

Ask about these chemicals locally

CDC: ask the health or environmental department, or EPA, whether to also test for volatile organic compounds, lead, arsenic, mercury, radium, pesticides or herbicides, and other chemicals or specific germs. VOCs to ask about include benzene, carbon tetrachloride, toluene, trichloroethylene, and MTBE — which ones depend on where you live.

EPA Safe Drinking Water Hotline, cited by CDC: (800) 426-4791.

EPA symptom-to-test chart (also in the 2005 fact sheet)

EPA’s Protect Your Home’s Water page and EPA 816-F-05-013 (May 2005) list common conditions and what to consider testing for. Not every substance is an immediate health risk; some affect appearance, taste, or odor.

See also iron stains and rotten-egg odor.

Who should run the test

CDC: use a state-certified laboratory. Local or state health or environmental departments often test for nitrates, total coliforms, fecal coliforms, VOCs, and pH, or they can point you to licensed laboratories.

EPA: only use laboratories certified to do drinking water testing. EPA cannot test residential drinking water on request. Find your state program via EPA certified-lab contacts (last updated 11 August 2026).

On this site: Minnesota labs · Pennsylvania labs.

After the results

This how-to is not a filter guide. After annual lab testing, compare filtration methods on DIY Kit Index if you still want point-of-use treatment: pitcher vs under-sink vs RO method comparison.

CDC: if results show harmful germs or chemicals, consider drinking bottled water or another safe source, and contact the local health or environmental department. They can help interpret results and may recommend more frequent testing.

EPA: if a contaminant exceeds health standards, contact the public health department and have the well re-tested to confirm. Some bacterial problems can be addressed with disinfection (chlorine, ozone, ultraviolet light). Depending on the contaminant, concentration, and well condition, you may need a new source or a new well. EPA points to CDC’s household water treatment information rather than to a product ranking.

If well testing sits beside rental or flip income on a Schedule C next to W-2 wages, the tax kit tracks quarterly reserves — not tax advice. See the 2026 W-2 + 1099 side-hustle tax spreadsheet. Optional: $29 workbook on Gumroad.