How to Test Your Home's Drinking Water (And What to Do With the Results)

Testing your drinking water is one of the most useful things you can do before buying a filter — and one of the most overlooked. Most people skip it entirely, buy a filter based on a general recommendation, and hope for the best.

The problem with that approach is that water quality varies significantly by location, by housing age, and even by the specific pipes in your home. Your ZIP code data tells you about your water system's recent history. But what comes out of your tap depends on a lot more than the utility's aggregate record.

A test tells you exactly what you're dealing with.

Strip kits vs lab kits: which do you need?

There are two fundamentally different kinds of home water tests, and they serve different purposes.

DIY strip kits give you results in minutes at home. You dip a test strip in a water sample, wait, and match the resulting color to a chart. They're inexpensive (usually under $30), require no shipping, and are genuinely useful for quick screening. The tradeoff is precision — strips tell you whether a contaminant is roughly present above a threshold, not exactly how much is there. They also test for fewer parameters than lab kits.

Lab mail-in kits are a different category entirely. You collect a water sample at home, mail it to a certified laboratory, and receive a detailed report in 5–20 business days depending on the test. They're more expensive ($50–$200+), but the results are certified, quantified, and genuinely actionable. A good lab report tells you the concentration of each contaminant, how it compares to EPA limits, and what filtration technology would address it.

For most people, the recommendation is: start with a lab kit once to establish a baseline, then use DIY strips for routine monitoring between lab tests.

When to use a DIY strip kit

Strip kits are the right choice when:

• You want a quick check and don't need certified results
• You're monitoring whether a filter is still working effectively
• You're on a tight budget and want a first indication of whether testing is worth pursuing further
• You just moved into a new home and want a quick overview before committing to a lab test

When to use a lab kit

A certified lab test is the right choice when:

• You're buying or moving into a home and want a definitive baseline
• Your ZIP code data shows elevated risk for lead, PFAS, or nitrates
• You have young children, a pregnant household member, or immunocompromised individuals
• Your home was built before 1986 (potential lead pipes or solder)
• You're on a private well
• You've noticed changes in taste, odor, or appearance of your water
• You want to verify that your current filter is actually working

The best lab kit for city water

If your home is on municipal water, the Tap Score Essential City Water Test is the most consistently recommended option across independent review sites, and the one picked by NYT Wirecutter as best in class.

What sets it apart from competitors isn't just what it tests for — it's how the results are presented. Instead of a dense PDF of raw numbers, Tap Score produces an interactive digital dashboard that color-codes each result as safe, satisfactory, or needs attention, with plain-English explanations of what each finding means and what to do about it. For someone without a chemistry background, this makes a significant difference.

The best lab kit for well water

Well water testing has different priorities than city water. Municipal utilities treat for bacteria and regulate for common contaminants. Private wells don't have that safety net -- they need annual testing at minimum, and the contaminant list is different.

For well owners, the same Tap Score network offers an advanced well water kit that tests for the specific contaminants most likely to be problematic in groundwater: bacteria, nitrates, arsenic, iron, manganese, lead, and volatile organic compounds. The CDC recommends testing well water for bacteria and nitrates at least once per year.

If your area has known PFAS concerns

PFAS (per- and polyfluoroalkyl substances) cannot be detected with DIY test strips. Detecting them requires specialized laboratory equipment and is one of the few areas where you have no choice but to use a certified lab kit.

If your ZIP code shows medium or high PFAS risk -- particularly if you're near a military base, airport, industrial facility, or a water system with a known contamination history -- a dedicated PFAS test is worth doing before investing in filtration. Not all filters address PFAS, and knowing whether you actually have a problem helps you choose the right one.

How to read your results and choose the right filter

Once your results come back, the action depends on what was found:

Lead detected above 15 ppb -- Your priority is a filter certified to NSF/ANSI 53 for lead reduction. A faucet-mount or under-sink carbon block filter handles this well. If you're on a private well with very high lead, an RO system is worth considering.

PFAS detected above EPA MCL (4 ppt for PFOA/PFOS) -- Only reverse osmosis and certain specialized carbon block filters remove PFAS reliably. Look for filters certified to NSF/ANSI 58 (RO systems) or NSF/ANSI 473 (PFAS-specific carbon filters).

Nitrates above 10 mg/L -- This is primarily a risk for infants and pregnant women, and it requires reverse osmosis. Standard carbon filters do not remove nitrates.

Bacteria detected -- A UV filter or RO system addresses bacteria. Carbon filters alone do not.

High hardness (above 150 mg/L as CaCO3) -- A water softener addresses hardness throughout the home. For drinking water specifically, an RO system also removes hardness minerals.

Chlorine/disinfection byproducts -- A standard activated carbon filter handles this well. This is the easiest problem to solve.

Nothing detected above limits -- Your filter choice is primarily about taste preference and peace of mind rather than safety. A basic carbon pitcher or faucet filter is sufficient.

How often should you test?

For municipal water, testing once when you move in and every 2--3 years afterward is reasonable. Test sooner if you notice changes in taste, odor, or color, or if your utility issues a notice about a main break or treatment change.

For well water, the CDC recommends annual testing for bacteria and nitrates at minimum. Test more frequently if you're near agricultural land (nitrate risk) or if you have young children in the household.

After installing a new filter, a follow-up test 3--6 months later confirms it's working as expected.

Links on this page are affiliate links. We may earn a commission if you purchase at no extra cost to you. We recommend products based on certifications, independent testing, and consistent reviews -- not commission rates.