Affiliate disclosure: Private Well Guide (privatewellguide.com) earns a commission from some links on this page, at no extra cost to you. We don’t test water or products ourselves. This guide summarizes published guidance from the EPA, CDC, USGS, state agencies and university extension services, linked throughout.
Health note: This is general information, not medical advice. For any decision about your family’s health, rely on results from a state-certified laboratory and talk to your local or state health department.
If your water comes from a private well, nobody else is checking it. More than 43 million people, about 15% of the U.S. population, rely on domestic wells, and USGS notes that those wells aren’t regulated by the federal Safe Drinking Water Act or, in most cases, by state law. The CDC puts it plainly: “Government officials do not regulate, treat, or monitor tap water from private wells.”
That makes testing your job. This guide covers what to test, when, where to send samples, and how to use the results.
The short version
- Every year: test for total coliform bacteria, nitrates, total dissolved solids (TDS) and pH. CDC and EPA both recommend this baseline.
- Add local contaminants: ask your local health department what’s common where you live, for example arsenic, uranium, radon or PFAS.
- Use a state-certified lab. Both CDC and EPA say so.
- Test right away after flooding, well repairs, or any change in taste, color or smell.
- If a health-related result is high, contact your health department and retest to confirm before you buy treatment equipment (EPA).
Why you can’t judge well water by looking at it
Many of the contaminants that matter most, including bacteria, nitrate and arsenic, have no color, taste or smell. Iron and hardness are easy to notice, but they’re mostly nuisances. A clear, good-tasting glass of water tells you very little about whether it’s safe.
Regular testing also builds a record. EPA’s home water testing fact sheet notes that a history of results helps you spot changes, and it can help if someone later damages your water supply.
What to test for
The annual baseline
| Test | Why it matters |
|---|---|
| Total coliform bacteria | An indicator that disease-causing germs may be getting into the well (CDC) |
| Nitrate | High levels can make infants seriously ill (EPA) |
| pH | Water that’s too acidic or basic can damage pipes, and corrosion can release metals like lead (CDC) |
| Total dissolved solids | General mineral content; affects taste and scale (CDC) |
Based on where you live and what’s nearby
EPA publishes a list of nearby conditions and the tests they call for. For example:
- Intensive agriculture nearby → nitrate, nitrite, pesticides, coliform
- Lead-containing plumbing → pH, lead, copper
- Radon-rich region → radon
- Gas drilling nearby → chloride, sodium, barium, strontium
- Stained fixtures or laundry → iron, copper, manganese
- Scale, or soap that won’t lather → hardness
Some contaminants come from the rock itself. USGS estimates that about 2.1 million people may use domestic wells with arsenic above 10 µg/L, EPA’s limit for public water.
Full checklist: What to Test Your Well Water For (and What You Can Skip)
How often to test
At least once a year for the baseline (CDC). Test again right away if:
- There’s flooding, land disturbance or a new waste site near your well
- You repair or replace any part of the well system
- The water’s taste, color or smell changes
- Someone in the home becomes pregnant, or a child starts living with you
CDC also recommends checking the well for mechanical problems every spring.
Details, including testing before you buy a home: How Often Should You Test Well Water? Annual, After Floods, Before Buying
Where to get your water tested
You have three realistic options:
- Your local or state health department. Many test for coliform, nitrate and other common problems. EPA notes some may test private wells for free.
- A state-certified lab near you. EPA keeps a directory of each state’s lab certification program Find a state-certified lab (EPA directory) →.
- A mail-in lab kit. You collect the sample at home and ship it to a lab. Tap Score’s well kits, for example, send samples to what the company describes as an independent, accredited lab Tap Score: Essential well water test →.
DIY strips are fine for quick checks, such as confirming a softener is working, but they aren’t a substitute for a lab when health decisions are involved. A UMass Amherst study found that home test kit quality “can vary widely.”
Compare the options: Tap Score vs Your State-Certified Lab vs DIY Strips · Best Well Water Test Kits 2026: DIY Kits vs Mail-In Labs
Reading your results
Your report will list each contaminant, the amount found, and its units (mg/L, µg/L and so on). Most labs compare results to EPA’s standards for public water systems. Those don’t legally apply to private wells, but they’re the standard yardsticks. A few key ones, from EPA’s drinking water regulations and secondary standards:
| Contaminant | EPA reference level |
|---|---|
| Total coliform | Goal of zero |
| Nitrate (as nitrogen) | 10 mg/L |
| Arsenic | 0.010 mg/L (10 µg/L) |
| Uranium | 30 µg/L |
| Iron (aesthetic) | 0.3 mg/L |
| Manganese (aesthetic) | 0.05 mg/L |
| pH (aesthetic) | 6.5–8.5 |
How to decode the rest of your report: How to Read Your Well Water Test Results (MCLs, ppm and ppb Explained)
If something comes back high
- If a health-related contaminant is high, follow CDC’s advice: consider bottled water or another safe source for drinking, and contact your local health or environmental department (CDC).
- Retest to confirm the result (EPA).
- Match treatment to the specific problem, and buy only equipment certified for that contaminant.
Contaminant guides:
– Bacteria: Coliform and E. coli in Well Water: What a Positive Test Means and How to Shock Chlorinate a Well, Step by Step
– Nitrates: Nitrates in Well Water: Health Risks, Limits and Fixes
– Arsenic: Arsenic in Well Water: Where It Comes From and How to Remove It
– Lead: Lead in Well Water: Testing Your Pipes, Pump and Fixtures
– PFAS: PFAS in Private Wells: Testing and Treatment
– Radon: Radon in Well Water: Should You Test?
– Iron and hardness: Hard Water, Iron and Manganese in Wells: Stains, Smells and Fixes
– Treatment overview: Well Water Treatment Options: UV vs RO vs Softener vs Whole-House Filter
Protecting your well between tests
From EPA’s private well guidance:
- Slope the ground so runoff drains away from the well.
- Keep a sealed well cap in good condition.
- Keep fertilizers, pesticides, fuels and other chemicals away from the well.
- Pump and inspect your septic system as often as your health department recommends.
- Periodically check for cracked casing, a damaged cap, or settling around the seal.
- Hire a licensed well contractor for new wells, repairs or abandoning an old well.
- Keep records of maintenance and test results.
FAQ
Can I test my well water myself?
You can collect the sample yourself, using a lab’s kit and instructions. For results you’ll base health decisions on, CDC and EPA recommend a state-certified lab.
Does boiling make well water safe?
Boiling can kill germs. It does not remove nitrate; Penn State Extension notes boiling actually increases nitrate concentration as water evaporates. CDC also warns that water contaminated with fuel or toxic chemicals won’t be made safe by boiling.
Where do I find a certified lab?
Start with your county health department, or use EPA’s state lab certification directory. CDC also lists EPA’s Safe Drinking Water Hotline, (800) 426-4791.
Sources
- CDC, Guidelines for Testing Well Water: https://www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html
- CDC, How to Disinfect Wells After an Emergency: https://www.cdc.gov/water-emergency/about/how-to-disinfect-wells-after-an-emergency.html
- EPA, Protect Your Home’s Water: https://www.epa.gov/privatewells/protect-your-homes-water
- EPA, National Primary Drinking Water Regulations: https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
- EPA, Secondary Drinking Water Standards: https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals
- EPA, Home Water Testing fact sheet: https://www.epa.gov/sites/default/files/2015-05/documents/epa816f05013.pdf
- EPA, Certified lab contacts: https://www.epa.gov/dwlabcert/contact-information-certification-programs-and-certified-laboratories-drinking-water
- USGS, Domestic (Private) Supply Wells: https://www.usgs.gov/mission-areas/water-resources/science/domestic-private-supply-wells
- USGS, Arsenic in private wells: https://www.usgs.gov/news/national-news-release/study-estimates-about-21-million-people-using-wells-high-arsenic
- UMass Amherst, home water test kit study: https://www.umass.edu/engineering/news/kumpel-home-water-tests
- Penn State Extension, Nitrates in Drinking Water: https://extension.psu.edu/nitrates-in-drinking-water