How many Americans use private wells?

EPA says around 15 percent of the U.S. population, more than 43 million people, rely on private wells for drinking water.

Where do I find a certified lab?

Your state's drinking water laboratory certification program lists them. Your local health department can point you to it, and some offer testing themselves.

How to test well water

TapBuff · Updated Oct. 4, 2026 · 2 min read

Test a private well every year for total coliform bacteria, nitrates, total dissolved solids and pH, using a laboratory certified for drinking water. Test again right away if anything changes: the taste, the color, a flood, new well parts, or a problem reported nearby.

No report is coming

If your water comes from your own well, no utility tests it and no annual report arrives. EPA is direct about it: private wells are "not regulated by the Federal Government under the Safe Drinking Water Act nor by most state governments and laws," and "private well owners are responsible for delivering safe drinking water to their households."

That covers a lot of people. EPA says around 15 percent of the U.S. population, over 43 million people, drink from private wells.

What to test for every year

EPA's advice is to "test your private well annually for total coliform bacteria, nitrates, total dissolved solids, and pH levels."

Total coliform bacteria. A sign that surface water or waste may be getting into the well. Many labs test for E. coli alongside it.
Nitrates. Common near farm fields, lawns and septic systems. EPA's legal limit for public water is 10 ppm, and the same number is a sensible line for a well.
Total dissolved solids. A broad measure of minerals and salts. A sudden change is a reason to look closer.
pH. Water that is too acidic can pull lead and copper out of plumbing.

What else to consider

Beyond the yearly four, what is worth testing depends on where you live. Arsenic and uranium occur naturally in some regions' groundwater. Wells near industrial sites, airports or military bases may be worth testing for PFAS. Your state or county health department knows what turns up locally, and is the best first call.

When to test again

EPA says to test right away if there are known groundwater problems in your area, if conditions near the well have changed significantly, if you replace parts of the well system, or if you notice a change in the water. That includes a flood, a new taste, odor or color, or a spill nearby.

Test more often if a baby, a pregnant or nursing person, or an older adult lives in the house.

Use a certified lab

EPA's advice is short: "Only use laboratories that are certified to do drinking water testing." Your state runs the certification program, and your local health department can point you to a list. Home test strips are useful for a quick check, but they are not a substitute for a lab result.

After the results

Once you know what is in the water, the fix follows from the contaminant, not the brand. Each contaminant page names the NSF/ANSI certification claim that addresses it, and the standards decoder explains what each number on a filter box means. If your home is on a public system after all, look it up instead:

Questions people ask

Does the government test private wells?: No. EPA says private wells are not regulated by the federal government under the Safe Drinking Water Act, nor by most state governments. The owner is responsible for the water's safety.
How many Americans use private wells?: EPA says around 15 percent of the U.S. population, more than 43 million people, rely on private wells for drinking water.
Where do I find a certified lab?: Your state's drinking water laboratory certification program lists them. Your local health department can point you to it, and some offer testing themselves.

Sources

Private Drinking Water Wells, U.S. EPA. Checked Oct. 4, 2026.
Protect Your Home's Water, U.S. EPA. Checked Oct. 4, 2026.