Lab tests cost money, and “test for everything” panels can cost several times more than a basic one. Both CDC and EPA say the same thing: test for the baseline every year, then add tests based on the specific risks around your well.
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Step 1: The baseline every well needs
Test at least once a year for these four (CDC, EPA):
- Total coliform bacteria. If positive, labs typically also test for E. coli or fecal coliform, which point to contamination from human or animal waste.
- Nitrate. CDC says all well owners should test for nitrate at least once a year.
- pH. Corrosive water can pull lead and copper from plumbing.
- Total dissolved solids (TDS). A general measure of dissolved minerals.
Your health department or a certified lab can usually run this panel. Tap Score vs Your State-Certified Lab vs DIY Strips
Step 2: Add tests based on what’s around you
EPA’s list of conditions and the tests they call for:
| If this applies to you… | …consider testing for |
|---|---|
| Recurring stomach or intestinal illness in the household | Coliform bacteria |
| Plumbing or service lines that may contain lead | pH, lead, copper |
| Radon in indoor air, or a radon-rich region | Radon |
| Corroding pipes or plumbing | Corrosion, pH, lead |
| Intensive agriculture nearby | Nitrate, nitrite, pesticides, coliform |
| Coal or other mining nearby | Metals, pH, corrosion |
| Gas drilling nearby | Chloride, sodium, barium, strontium |
| Dump, junkyard, landfill, factory, gas station or dry cleaner nearby | Volatile organic compounds (VOCs), TDS, pH, sulfate, chloride, metals |
| Gasoline or fuel-oil odor, or buried fuel tanks nearby | VOCs |
| Objectionable taste or smell | Hydrogen sulfide, corrosion, metals |
| Stained fixtures or laundry | Iron, copper, manganese |
| Salty taste, seawater, or a heavily salted road nearby | Chloride, TDS, sodium |
| Scale, or soap that won’t lather | Hardness |
| Treatment equipment wearing out quickly | pH, corrosion |
| You need a softener for hardness | Manganese, iron |
| Cloudy, frothy or colored water | Color, detergents |
CDC adds a list of chemicals to ask your health department about: VOCs, lead, arsenic, mercury, radium, pesticides and herbicides.
Step 3: Test at least once for your area’s natural contaminants
Some contaminants come from the rock and soil, not from anything you or your neighbors did:
- Arsenic. USGS estimates about 2.1 million people may use wells with arsenic above 10 µg/L. Arsenic in Well Water: Where It Comes From and How to Remove It
- Uranium and radium. These are regulated for public water at 30 µg/L (uranium) and 5 pCi/L (combined radium) (EPA). Connecticut’s public health department notes that uranium results can vary from season to season and suggests retesting whenever a result is above 10 µg/L.
- Radon. Wisconsin DNR notes that you can’t know your well’s radon level without testing. Radon in Well Water: Should You Test?
Neighbors’ results can differ from yours, so test your own well.
Situations that call for specific tests
- Pregnancy or an infant in the home: nitrate. EPA suggests testing early in pregnancy, before bringing a baby home, and during the baby’s first six months (EPA fact sheet). Nitrates in Well Water: Health Risks, Limits and Fixes
- Older home or brass fixtures: lead. Lead in Well Water: Testing Your Pipes, Pump and Fixtures
- Near a military base, airport, industrial site, or firefighting-foam use: ask your state about PFAS. PFAS in Private Wells: Testing and Treatment
- A fuel or chemical spill nearby: VOCs (EPA fact sheet).
What you can usually skip
- Tests with no link to your situation. In CDC’s words: “spend time identifying potential problems as these tests can be expensive.” EPA’s fact sheet says to “limit them to possible problems specific to your situation.”
- Re-running one-time geology tests every year. Once you have a baseline for arsenic or uranium, follow your health department’s advice on how often to recheck. Annual retesting isn’t usually the default. Recheck sooner if your water or surroundings change.
- Hardness and iron as health tests. They matter for plumbing and appliances. Penn State Extension notes that iron and manganese generally carry aesthetic standards; “manganese has an EPA lifetime health advisory level of 0.3 mg/L.” A cheap DIY strip can track hardness between lab tests.
Building your panel
| Your situation | Suggested starting panel |
|---|---|
| Any well, every year | Coliform (+ E. coli), nitrate, pH, TDS |
| First test on a new-to-you well | Baseline + arsenic, lead, iron, manganese, hardness, plus local add-ons from your health department |
| Farm country | Baseline + nitrite and the pesticides your health department suggests |
| Radon or uranium region | Baseline + radon, uranium, gross alpha/radium |
| Near fuel or industry | Baseline + VOCs (and PFAS if your state recommends it) |
Mail-in lab kits bundle many of these tests. Tap Score’s Essential Well Water Test, for example, lists heavy metals, minerals, hardness, nitrate, nitrite and coliform bacteria including E. coli Tap Score: Essential well water test →. Compare it with what your county lab offers. Best Well Water Test Kits 2026: DIY Kits vs Mail-In Labs
FAQ
Is a “comprehensive” panel worth it? For a first test on a well you’ve just bought, a broad panel gives you a useful baseline. “After that, most homeowners use a targeted annual panel, following their health department’s guidance.”
Should I test before or after my softener or filter? Test raw (untreated) water to learn what’s in the well, and treated water to confirm your equipment works. New Jersey’s home-sale rules, for example, require testing untreated groundwater.
Sources
- CDC, Guidelines for Testing Well Water: https://www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html
- EPA, Protect Your Home’s Water: https://www.epa.gov/privatewells/protect-your-homes-water
- EPA, Home Water Testing fact sheet: https://www.epa.gov/sites/default/files/2015-05/documents/epa816f05013.pdf
- EPA, National Primary Drinking Water Regulations: https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
- USGS, arsenic estimate: https://www.usgs.gov/news/national-news-release/study-estimates-about-21-million-people-using-wells-high-arsenic
- Connecticut DPH, Uranium in Drinking Water: https://portal.ct.gov/-/media/departments-and-agencies/dph/dph/environmental_health/what-you-need-to-know-about-uranium-in-drinking-water-pdf.pdf
- Wisconsin DNR, Radon in private well water: https://dnr.wisconsin.gov/topic/Wells/radon.html
- Penn State Extension, Iron and Manganese: https://extension.psu.edu/iron-and-manganese-in-private-water-systems
- NJDEP, Private Well Testing Act: https://dep.nj.gov/privatewells/pwta/