How to Test Your Tap Water at Home: Strips, Mail-In Kits, and Certified Labs

The most reliable way to test your tap water is to send a sample to a state-certified drinking water laboratory. Home test strips are fine for a quick look at things like hardness, chlorine or pH, but research shows many are not sensitive enough to detect lead at levels that matter. If a result will shape a health decision, such as whether to filter for lead or whether a well is safe for a baby, use a certified lab. EPA, CDC and state health departments all point people to certified labs for exactly this reason.

Below: what each testing option can and cannot do, what to test for, when to test, and how to find a lab.

First: do you need to test at all?

If you are on public water, your utility already tests regularly and publishes the results in its annual Consumer Confidence Report. Start there. Our guide on how to read your water quality report explains it, and you can see your utility’s grade and EPA record by searching your ZIP code.

A home test is still worth doing when the issue is in your own building, not the utility’s water:

Lead and copper. These usually come from service lines, solder and fixtures. The utility’s numbers come from a sample of homes, not yours. See how to find out if you have a lead pipe.
A change you notice, such as a new taste, smell or color. See why tap water smells or tastes strange and cloudy, brown or discolored water.
Checking a filter you rely on.

If you have a private well, testing is your job. Private wells are not regulated under the federal Safe Drinking Water Act, so nobody else tests that water for you. (Some states and localities set their own rules.) Our well water testing guide goes deeper.

Option 1: Test strips and home kits

What they are: strips or color-change kits you dip in water and read at home.

What they’re good for: a quick screen for common water properties such as hardness, pH, chlorine, and sometimes nitrate. They can help you notice that something changed.

Limits:

Lead detection is a weak spot. In a 2021 Virginia Tech study, researchers tested 16 brands of at-home lead test kits. Most (12 of 16) were not suitable for drinking water, with detection limits of 5 to 20 milligrams per liter. That is hundreds of times higher than EPA’s lead action level of 15 parts per billion (0.015 mg/L), which is set to drop to 10 ppb under the 2024 Lead and Copper Rule Improvements. Some simple yes/no strips did detect dissolved lead at relevant levels, but they missed particulate lead, meaning small bits of lead that break off pipes. The authors noted there is no certification body for the accuracy of at-home lead test kits.
Results can be misread. The San Francisco Public Utilities Commission warns that home kits can give misleading results, such as when a color strip does not fully develop, and that results vary by brand and contaminant.
No bacteria confirmation you can rely on for health decisions.

Bottom line: treat a strip as a first look, not an answer. SFPUC advises confirming any poor result with a laboratory that uses certified methods.

Option 2: Mail-in lab kits

What they are: you order a kit online, collect a sample at home, and mail it to a lab. You get results by email or online.

What they’re good for: convenience, and a wider range of contaminants than strips. The quality depends almost entirely on the lab doing the analysis.

What to check before you buy:

Is the analyzing lab certified for drinking water by a state program, for the specific contaminants you are paying for? SFPUC cautions that some home-test products use labs that are not certified, with methods that should not be relied on for safety decisions.
Which lab actually runs the sample. Ask the company to name it, then check that lab against your state’s certification list (see below).
Sampling instructions. For lead, first-draw water that has sat in your pipes overnight usually shows the highest levels. Follow the kit exactly.

A “certified lab” claim in marketing is not proof. Verify it yourself.

Option 3: A state-certified lab, directly

What it is: you contact a lab certified by your state for drinking water testing. The lab gives you sterile bottles and instructions. Some local health departments run or arrange testing themselves.

Why it’s the gold standard: states certify labs to run approved methods with quality controls. This is the kind of result that public health agencies rely on. EPA encourages homeowners who want independent testing to contact a state-certified drinking water laboratory, and CDC tells well owners to “use a state-certified laboratory to test your water.”

Cost: prices vary by lab, state and the contaminants you choose, so ask for a quote. For well owners, EPA notes that your local health department “may provide private well testing for free.” Ask before paying.

How to find a certified lab

Use EPA’s state lab certification list. EPA does not test home water itself, but it keeps a list of each state’s drinking water laboratory certification program. Each program publishes its certified labs.
Call your local or state health department or environmental agency. CDC says they can provide a list of state-certified labs in your area.
Ask the lab whether it is certified for each contaminant and method you need. Certification is usually specific to the test, not the whole lab.
Ask your water utility. Your utility may offer lead testing or be able to point you to local certified labs.

What to test for

On public water

Lead (and often copper), especially if your home has or may have a lead service line, or was built before the 1986 federal ban on lead solder in drinking water plumbing.
Anything specific to your situation, such as a concern listed for your utility, or a filter you want to check.

You usually do not need a broad panel. Your utility already tests for regulated contaminants. Read its report first, then fill the gaps.

On a private well

CDC and EPA recommend testing at least once a year for:

Total coliform bacteria
Nitrate
Total dissolved solids
pH

CDC says “all well owners should test for nitrates at least once every year.” Beyond that, test for contaminants common in your area. EPA gives examples: nitrate, nitrite and pesticides near intensive farming; metals near mining; volatile organic compounds near gas stations or dry cleaners. Your local health department can tell you what is common where you live, such as arsenic, radium or uranium. See also nitrate in tap water.

When to test

For private wells, CDC recommends testing more often, beyond the yearly check, when:

You hear of well water problems in your area
Flooding, land disturbance or nearby waste sites affect your well
You repair or replace any part of the well system
You notice a change in taste, color or smell
Someone in your home becomes pregnant
A child comes to live with you

EPA adds that households with infants, older adults, or pregnant or nursing members may need more frequent testing.

For public water, good times to test are when you move into an older home, when you are expecting a baby or preparing infant formula (see tap water for baby formula), after plumbing work, or when the water changes noticeably.

If you are under a boil water notice, follow your utility’s instructions rather than testing yourself. See what to do during a boil water advisory.

After you get results

Compare each result to the EPA limit (MCL) or action level, using matching units. Our CCR guide explains ppm, ppb and ppt.
Retest to confirm any surprising result, ideally with a certified lab.
For lead, follow the steps in our lead guide, including using cold water for drinking and cooking and choosing a filter certified to NSF/ANSI 53 for lead.
For a positive bacteria result in a well, contact your local health department for guidance on disinfection and retesting.
Talk to a doctor if anyone in your home is pregnant, an infant, or has a health condition and a result is above a limit.