How WaterTestAtlas Works

Tell us about your water

It starts with a few questions in the test finder, which also opens from the ZIP code box on our water testing home page. We ask for your ZIP code, where your water comes from (a private well or a public system), why you are testing, anything you have noticed about the water, and whether you have a filter or treatment system. If you don't know an answer, several questions let you choose "Not sure", and the plan still works.

Your ZIP code tells us which state's certified labs can test your water and which local conditions matter. We don't need your name or email to build a plan.

Your test plan

Your answers become a test plan in three groups, and every test in it says why it is there.

• Essential. The tests that matter for almost everyone with your kind of water. For a private well, CDC recommends testing at least once every year for total coliform bacteria, nitrates, total dissolved solids and pH.
• Because of where you live. Tests suggested by local conditions, such as a contaminant known to occur in wells in your area.
• For your situation. Tests that follow from your answers, such as a home sale, a baby or pregnancy in the home, or a change in how the water looks, smells or tastes.

The plan also lists tests we don't prioritize for you, with the reason and the source behind it. Testing for everything is rarely the best use of your money, and a short, well-chosen plan is easier to act on. The plan comes from fixed, published rules, not from an AI model.

Choose a lab

For the tests in your plan, we show labs certified by your state to test drinking water, and for each test that has a state certification of its own. Up to three of them carry a label:

• Best value: the lowest total price for your tests, shipping included where the lab charges it.
• Easiest: the simplest way to get your sample to the lab, such as a mail-in kit with return shipping included.
• Fastest: the shortest stated turnaround for your results.

The lab is always named, with its certification and where each price comes from. Some labs take orders through WaterTestAtlas; for others, you order directly from the lab, and we show you how. What we earn on an order never changes the ranking. You can also browse the certified lab directory on your own.

Collect and ship your sample

The lab sends bottles and instructions, or tells you where to pick them up. Follow its instructions exactly: the bottle, the tap, how long to run the water and how to store the sample all affect the result.

Bacteria samples are the most time-sensitive. Under federal rules for public water systems, the time from collecting a bacteria sample to starting the lab's test may not exceed 30 hours^[2], and labs plan their bacteria schedules around limits like this. Collect a bacteria sample only on a day the lab can receive it in time, and check its receiving days before you fill the bottle. The bacteria water test page covers the steps.

If the test is for a home sale or a mortgage, ask your lender or agent before you order: who must collect the sample, and which labs they accept. Their rules come first.

Understand your results

When the lab's report arrives, bring it to check your water test results. You can upload the report or type the values in yourself.

If you upload it, an AI model reads the values off the report. It only copies numbers; it does not decide what they mean. You then check every row against your report and correct anything that was read wrong. Nothing is interpreted until you confirm.

Each confirmed value is then compared with the benchmark it is measured against, such as an EPA limit or a state guideline, using fixed rules and versioned data. You see where each result falls, what the benchmark is and what to do next, in plain language.

What happens next

If every result is below its benchmark, no treatment is needed. Keep the report: it is a baseline to compare with next time. For a private well, CDC recommends testing at least once every year.

If a result is above a benchmark, the next step is usually to retest to confirm it, and to talk with your health department, which CDC says can help you understand your results and what to do next. Compare treatment options only after a certified-lab result confirms a problem, and match them to that result.

If you have an account, your results stay private to you, and you can export or delete them at any time. You can read more about WaterTestAtlas, including how we stay independent.