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Well Water Testing: What to Test For, How Often and Cost

Updated October 31, 2026 · General information, not medical or plumbing advice

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The short answer: Test your private well at least once a year at a state-certified lab. CDC's annual panel is total coliform bacteria, nitrates, total dissolved solids and pH. Test sooner after flooding, repairs, or any change in taste, color or smell. Ask your health department what else to add for your area.

EPA says the quality and safety of private well water is not regulated by the federal government or by most state governments. That makes you the one who has to check it. EPA also cites a U.S. Geological Survey study of 2,100 private wells: about one in five contained at least one contaminant above a human-health benchmark.

Safety first. Taste, smell and color do not tell you whether water is safe to drink. For any health-related test, use a state-certified lab. Home kits are screening only. If a lab test comes back positive for bacteria or a harmful chemical, follow your health department's advice.

The yearly test (CDC)

Test	What it tells you
Total coliform bacteria	A high count suggests harmful germs, including certain viruses, bacteria and parasites, may also be in the water.
E. coli or fecal coliform	A positive result likely means fecal contamination. It does not show which E. coli type is present.
Nitrate	CDC says all well owners should test every year. High levels can make people sick, especially babies.
Total dissolved solids (TDS)	Shows mineral content, which affects taste, appearance and scale.
pH	Affects pipes and can let heavy metals like lead leach into the water.

Source: CDC, Guidelines for Testing Well Water.

Other tests to ask about

CDC says to ask your health or environmental department about volatile organic compounds (VOCs), lead, arsenic, mercury, radium, and pesticides or herbicides. Which ones matter depends on where you live. For lead, CDC says testing is the only way to know if it has leached into your water.

For nuisance problems, ask a lab about iron, manganese, hardness, sulfate and chloride. EPA lists these as causes of staining, odor, salty taste and scale. They are not health threats at the recommended levels, but they affect how water looks and tastes and how well treatment works.

When to test sooner (CDC)

You are told about local well water problems.
Flooding, land disturbance or nearby waste disposal sites may affect your well.
You repair or replace any part of the well system.
The water's taste, color or smell changes.
Someone in the house becomes pregnant, or a child starts living with you.

How to get it done

Find a certified lab. CDC says your health department, environmental department or county government can give you a list of state-certified labs. The Safe Drinking Water Hotline is (800) 426-4791.
Follow the lab's sample instructions exactly. Labs differ. As one example, Kenosha County, Wisconsin says to use a cold tap without a swivel faucet, run the water 3 to 4 minutes, fill the bottle to the shoulder, and deliver it quickly. Kenosha gives a delivery deadline for bacteria samples (30 hours) and says nitrate samples must stay iced or the lab may reject them.
Ask your health department to explain the results. CDC says they can help you understand the results and what to do next.

What it costs

Prices vary by lab and change over time. One county public health lab in Wisconsin lists these prices (the page shows no year):

Test	Price
Bacteria	$35
Nitrate	$35
Fluoride	$35
All three	$90
Arsenic (sent to the state lab)	$36

Source: Kenosha County, Wisconsin. Check your own lab's current prices.

Home test kits

A home kit can be a cheap first look at things like hardness or iron. It is not a substitute for a certified lab for bacteria, nitrate, lead, arsenic or anything else tied to health. If a kit shows a problem, confirm it with a lab before you spend money on treatment.

Not sure what's wrong with your water?

Our free checker matches what you see, smell or taste to the likely cause, the test to ask for and the type of treatment that fits.

Open the well water checker

Start with a test

A state-certified lab test is the starting point for everything on this site. A home kit can be a cheap first screen, but it does not replace a lab test for anything health-related.

What to test for and how often See home screening kits

Common questions

How often should I test my well water?

CDC says to test at least once each year, and to check the well every spring for mechanical problems. Test sooner if the taste, color or smell changes, after flooding, or after any repair or replacement of part of the well system.

What should I test for every year?

CDC lists total coliform bacteria, nitrates, total dissolved solids and pH. It says nitrates are required for all well owners every year.

Can I use a home test kit?

Treat home kits as a screening step only. CDC's guidance is to use a state-certified laboratory to test your water, and our advice is to confirm any worrying kit result with a certified lab.

How much does a well water test cost?

It depends on the lab and the tests. One county public health lab in Wisconsin lists $35 each for bacteria, nitrate and fluoride, or $90 for all three. Check your own lab's current price list.

Sources