How to test the private well before closing
Have a certified lab run a well water test before closing, and make the deal depend on the result. At minimum, test for total coliform bacteria, nitrates, total dissolved solids and pH, then add whatever is common in your area. Ask your health department what that is, and have someone independent collect the sample.
What to test well water for before you buy
Once you close, the well's water is your job. EPA doesn't regulate private wells, so nobody tests it for you. CDC and EPA both say to test yearly for total coliform bacteria, nitrates, total dissolved solids and pH. Before a purchase, a wider panel makes sense, because this may be your last chance to ask the seller for a fix.
What else to add depends on your location and what's nearby. CDC lists arsenic, lead, mercury, radium, pesticides and volatile organic compounds as options to discuss with your health department. EPA matches tests to conditions:
- Nearby farms: nitrate, nitrite, pesticides and coliform.
- Lead or copper plumbing, or corroding pipes: pH, lead and copper.
- Radon in the home or the region: radon.
- Nearby gas stations, dry cleaners or landfills: volatile organic compounds and metals.
- Nearby gas drilling: chloride, sodium, barium and strontium.
- Stained fixtures or laundry: iron, copper and manganese.
State rules vary widely. Rhode Island, for example, has buyers test within 10 days of signing the purchase agreement, with licensed experts collecting the samples, and it protects buyers only if testing happens before closing. Your county or lender may also require specific tests, so ask them early.
How to order a well water test before buying a house
- Write it into the offer
Add a water test contingency so a poor result gives you options, and agree who picks the lab.
- Call the county health department
Ask what's common locally, what your state requires at sale, and if it offers free or cheap testing.
- Pick a certified lab
Use a state-certified drinking water lab. One guide notes that home test kits aren't accepted for real estate or lender needs.
- Control the sample
Have the lab or your inspector collect it. Bacteria samples can have a holding time of only 24 to 30 hours, so sample early in the week.
- Sample before any treatment
Ask for a sample ahead of any softener or filter, or you'll be testing the equipment instead of the well.
- Ask for the well's records
Request the well log, its depth, the ages of the pump and pressure tank, past test results and treatment manuals.
- Walk the wellhead
Look for a tight cap, an undamaged casing and ground that slopes away, and note nearby septic systems or fuel tanks.
Well water test results and the limits to compare them to
| Test | EPA benchmark | What a bad result means |
|---|---|---|
| Total coliform | Goal is zero | Germs may have a path into the water |
| E. coli | Should not be present | Likely human or animal waste contamination |
| Nitrate (as nitrogen) | 10 mg/L | A serious risk to infants under six months |
| Nitrite (as nitrogen) | 1 mg/L | Same infant risk as nitrate |
| Arsenic | 0.010 mg/L | Long-term skin, circulation and cancer risks |
| Uranium | 30 µg/L | Long-term cancer and kidney risks |
| Lead | Action level 0.015 mg/L, dropping to 0.010 in November 2027 | Harm to children's development |
| pH | Ask your lab | Water that's too acidic or basic can damage pipes and leach metals |
These limits are written for public water systems, and they're the usual yardstick for a well. Ask your health department to help you read the report. Washington's health department suggests a retest in six months if nitrate is 5 mg/L or higher.
If a well water test before buying a house comes back bad
Don't drink it until you know more. CDC suggests bottled water or another safe source, and EPA says to contact your health department and retest to confirm the problem.
Some problems clear up fast. EPA says high bacteria can often be controlled with disinfection such as chlorine, ozone or ultraviolet light. Others need filtration or distillation, and some mean a new water source or a new well. Hire a certified well driller for any changes to the well itself.
Ask your agent or attorney how your contract handles a failed test. Common requests are a fix and a passing retest before closing, a credit, or walking away. Get a quote before you decide, since treatment can carry ongoing costs.
How much does a well water test cost, and other questions
How much does a well water test cost?
One guide puts a basic bacteria test at about $25 to $75, a standard panel at about $100 to $250, and a full panel above $300 to $500. Prices vary by lab, and your health department may test for less.
Who pays for a well test when buying a house?
It depends on your contract and state. In Rhode Island, the buyer pays. Elsewhere, it's usually a point to negotiate, so ask your agent.
How often should I test my well after moving in?
At least once a year. Test again after flooding, well repairs, or a change in taste, color or smell, and when someone becomes pregnant or a child moves in.
What you’ll need
Sources: CDC, EPA, web.uri.edu, doh.wa.gov, inspectandtest.net
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.