How to test your well water

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Nobody tests a private well except you.

Federal drinking water rules stop at public water systems. The EPA says private wells aren't regulated by the federal government, and most states don't regulate them either. More than 43 million people in the US drink from private wells, according to the EPA.

That means the only test your well gets is the one you order. Penn State Extension says most private wells have at least 1 water quality problem. The Minnesota Department of Health says you can't see, smell or taste most contaminants.

Test for these 4 things every year.

The CDC and the EPA both recommend a yearly test for:

• Total coliform bacteria. These bacteria live on the ground surface and in the top few feet of soil. Finding them means something from the surface is getting into the well. Many labs also check for E. coli, which comes from human or animal waste. More on bacteria.
• Nitrate. It comes from fertilizer, manure and septic systems. Babies are the ones most at risk. More on nitrate.
• Total dissolved solids (TDS). This is the total amount of minerals and salts dissolved in the water. Penn State says to watch it over time, because a big jump from last year tells you something changed.
• pH. This tells you how acidic the water is. The EPA's guideline range for drinking water is 6.5 to 8.5.

Bacteria problems are common. Penn State found coliform bacteria in about 35 percent of the Pennsylvania wells it surveyed.

Test for arsenic and lead at least once.

The Minnesota Department of Health recommends testing at least once for arsenic and lead, and testing for manganese before a baby drinks the water. Lead can come from your own pipes and fixtures. The EPA says lead pipes are more likely in homes built before 1986.

What else to test for depends on where you live. The CDC's advice is to ask your local health department which contaminants show up in your area. That might be uranium, radon, PFAS, iron or hardness. Our county pages at /well-water/ show what other wells near you have turned up.

Test right away when something changes.

The CDC says to test outside your yearly schedule when:

• Your water changes taste, color or smell.
• You replace or repair any part of the well system.
• There's flooding, digging or a waste site near the well.
• You hear about well water problems in your area.
• Someone in the house is pregnant, or a child moves in.

Minnesota adds one more: test for bacteria any time the well is opened up for work. Older wells and wells under 50 feet deep are worth testing more often, because their water can change after heavy rain or snowmelt.

Ask the lab for bottles before you take a sample.

Use a lab certified by your state for drinking water. The lab sends sterile bottles and written instructions. Follow them exactly. Bacteria samples have to reach the lab fast. Wisconsin's limit is 30 hours from filling the bottle to the start of the test. Check which days the lab takes them before you fill the bottle.

Penn State says bacteria tests usually cost $20 to $40, and single tests range from a few dollars to over $100. Some states and counties test private wells for free or at a discount.

Questions people ask