Well Water Testing

Why test your well

If your home gets its water from a private well, testing it is your job. No utility checks the water for you, and no government agency samples it on a schedule. A lab test is the only way to know what is in the water you drink.

Private wells sit outside the federal drinking water rules. EPA's National Primary Drinking Water Regulations are legally enforceable standards and treatment techniques, but they apply to public water systems. EPA says the quality of water from private domestic wells is not regulated by the federal government under the Safe Drinking Water Act, nor by most state governments and laws. CDC puts it the same way: EPA's rules that protect public drinking water systems do not apply to privately owned wells. EPA's conclusion is direct: private well owners are responsible for the water they deliver to their households.

You are far from alone. EPA estimates that more than 23 million households^[1] in the United States rely on private wells for drinking water. That is around 15 percent^[1] of the U.S. population, or over 43 million^[1] people.

Wells do turn up contaminants. The U.S. Geological Survey studied about 2,100^[4] domestic wells in 48^[4] states, sampled in 1991–2004^[4]. It found that more than one in five (23 percent)^[4] of those wells had at least one contaminant at a concentration greater than a human-health benchmark. The contaminants most often found above a benchmark were inorganic chemicals, and all of them except nitrate came mainly from natural sources.

That last point matters for how you think about your own well. A well can pick up a contaminant from natural sources even when nothing nearby looks like a pollution source, so a quiet neighborhood is not a reason to skip the test. A clean result is also a useful outcome: it gives you a baseline to compare against, and it means no treatment is needed based on that result.

The yearly baseline: what to test every year

CDC's guidance is short: test your well water at least once every year for total coliform bacteria, nitrates, total dissolved solids and pH. CDC also says to use a state-certified laboratory for the test. These four tests are the baseline, the minimum that tells you whether anything has changed since last year.

• Total coliform bacteria. This is the yearly check for bacteria getting into your well or plumbing. Our bacteria water test guide explains what the test looks for and how to take a sterile sample. If a result comes back positive, our page on bacteria in well water walks through what it means and the steps that follow.
• Nitrate. Nitrate is the one common well contaminant that the USGS study found came mainly from human activity rather than natural sources. The federal limit that public systems must meet is 10 mg/L^[5], and it is a useful yardstick for a well result. Our nitrate water test guide covers who should pay closest attention and how to read the number.
• Total dissolved solids (TDS). TDS is a measure of everything dissolved in the water. It is not a single contaminant, and tracking it year to year shows you whether the makeup of your water is shifting.
• pH. pH tells you whether the water is acidic or basic. Like TDS, it is most useful as part of a record you compare from one year to the next.

Keep each year's report. Comparing results year to year is how the baseline earns its keep: a steady record is reassuring, and a jump in one value is a reason to look closer.

When to test outside the yearly schedule

CDC lists events that call for a test even if you tested recently. Have your well water tested if:

• You are notified that there are problems with well water in your area.
• There are problems near your well, such as flooding, land disturbances or nearby waste disposal sites.
• You replace or repair any part of your well system.
• You notice a change in your water's taste, color or smell.
• You or someone you live with becomes pregnant.
• A child starts living with you.

CDC also suggests checking the well itself every spring to make sure there are no mechanical problems. That inspection is separate from a water test, and it is a good moment to schedule the yearly sample.

Tests beyond the baseline

The baseline does not cover everything a well can contain. CDC says to contact your health department to find out what other germs or chemicals to test for based on where you live. Two common additions are arsenic, covered in our arsenic water test guide, and lead, covered in our lead water test guide. If you are not sure which tests fit your home, you can build a test plan in a few questions.

Testing for a situation

Some situations call for a specific set of tests, a specific deadline, or a result in a form someone else will accept. Here is how to approach the common ones.

Buying or refinancing a home with a well. If you are buying or refinancing a home with a private well, and especially if you are using a VA loan or an FHA loan, ask your lender or appraiser before you order anything: which tests the loan requires, what result counts as passing, how recent the result must be, and whether a particular person must collect the sample. A lender's list sets the minimum for the loan, not for your household, so it is worth adding the yearly baseline if the lender's list is shorter. Our guide to moving to a house with well water covers what to test before you buy, who should take the sample and how to time the test in the contract.

A new baby or a pregnancy in the home. CDC names both as reasons to test: when you or someone you live with becomes pregnant, and when a child starts living with you. Our nitrate guide covers what to know when an infant drinks the water.

After a flood or well repair. Flooding near the well and any repair or replacement of part of the well system are both on CDC's list. A bacteria test after the work tells you whether bacteria got into the water.

A change you can see, smell or taste. A change in your water's taste, color or smell is a reason to test, not an answer. The lab result tells you whether the change matters for health or is only a nuisance. If your well water smells like rotten eggs or turns brown, those pages walk through the likely causes and the test that confirms each one.

Testing by state

What to test for, and which labs you can use, depends on where you live. CDC recommends a state-certified laboratory for well tests and suggests asking your health department which other tests fit your area. EPA keeps a directory of state contacts and notes that while most states have zero or limited regulations for private drinking water wells, states do have programs to assist well owners.

Our state pages list certified labs, the tests they offer and how to get a sample to them. Pick your state below, or browse every state we cover.

If your state is not listed yet, your state or county health department is the best place to start. Ask which labs are certified for the tests you need and whether the department recommends any tests for your area.

What well water testing costs

The yearly baseline is the most common well test, so it is the price we track for well owners. The price below covers the bacteria, nitrate, total dissolved solids and pH tests from the certified labs we list, with the date we last checked each price.

from $300 drop-off Verified Nov 5, 2026 Panels that include the 4 CDC yearly tests · certified labs we list

What changes the price:

• How many tests you order. The baseline is a short list. A broad panel that adds metals, arsenic, lead or other chemicals costs more, so add tests for a reason, such as your health department's advice or a nearby problem.
• The lab you choose. Certified labs set their own prices, and the same test can cost different amounts at different labs in the same state.
• Shipping and the sample kit. Some prices include the bottles and return shipping; others add them. Some samples have a short window to reach the lab, which can mean paying for faster shipping.
• Drop-off. If a certified lab is close enough to deliver the sample yourself, you can skip shipping altogether.

For prices on single tests and broader panels, see our water testing cost guide. Before you pay, check for a public program: our page on free water testing covers health departments, universities and utilities, and what store and dealer tests are.

A home test kit does not give you a certified-lab result. For a decision about your household's drinking water, a lender requirement, or whether you need treatment at all, use a state-certified lab. Our guide on how to test water quality compares a lab test with a mail-in kit and test strips.

How to collect a well water sample

A well sample is easy to take, but small mistakes can spoil a result. Your lab's instructions are the rule: they are written for that lab's bottles and methods. The steps below cover what applies to most well kits.

1. Order first, then plan the day. Each test has its own bottle, and some bottles come with a preservative or are sterile. Read every bottle's instructions before you start, and plan around the one with the shortest window to reach the lab.
2. Check the shipping days. Many labs only receive samples on certain days. Collect close to a shipping or drop-off time so the sample is fresh when it arrives.
3. Pick the right tap. Use a cold-water tap you drink or cook from, usually the kitchen sink. If you have a softener, filter or other device, ask the lab whether to sample before it, after it, or both. Sampling before it tells you about the well; sampling after it tells you what you drink.
4. Remove attachments. Take off any aerator, hose or attachment on the faucet, unless your kit says otherwise.
5. Run the cold water. Let it run until it is steady and cool, so the sample comes from the well and not from water that sat in the pipes. Your lab's instructions give the exact time.
6. Fill without rinsing. Don't rinse out anything the lab put in a bottle. Don't touch the inside of a cap or bottle, especially a sterile bacteria bottle. Fill to the line and cap it tightly.
7. Label and send. Write the date, time, tap and whether the sample was taken before or after any device. Pack it the way the lab asks, with any cold pack it provides, and send it within the time the lab gives you.

Common mistakes to avoid

• Sampling from an outdoor spigot or a hose when you wanted to know about your drinking water.
• Sampling only after a filter or softener when you wanted to know about the well itself.
• Collecting on a day when the sample cannot reach the lab within its window.
• Comparing this year's result with last year's when the samples came from different taps.

When the report arrives, compare it with your earlier reports. If every result is within its benchmark, no treatment is needed based on that test, and the next step is simply to test again next year.