How do you find out what is in your tap water, and which tests matter?

1. Read the report. Every community water system must deliver a Consumer Confidence Report (CCR) to customers by July 1 and provide copies on request; systems serving 100,000 or more people must also post it online¹. It covers the source of your water, definitions of terms, a table of detected contaminants with their legal limits (MCL), health goals (MCLG) and likely sources, any violations, and educational notes on nitrate, arsenic and lead¹. These reports are hard going: a national sample of 30 was written at an 11th–14th grade reading level⁴, and smaller systems and vulnerable communities had poorer reports⁵. If yours is unclear, call the utility.

2. Check other public data. EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR 5) required 29 PFAS plus lithium to be measured between 2023 and 2025 at larger systems and a sample of small ones; results are searchable, but they do not show compliance with limits⁶. EWG's Tap Water Database compares utility results collected by states with legal limits and with its own, often stricter, non-enforceable health guidelines, so a legal system can still appear “above guideline”; it reflects utility testing, not your tap⁷.

3. Test your own tap. A report describes the water the utility delivers, not what your pipes add. In 32 Chicago homes with lead service lines, sequential sampling found the highest lead within the service lines, with peaks more than four times the first-draw results used for compliance⁸. Federal compliance sampling uses water that has stood motionless at least six hours in an interior cold-water tap⁹. For city water, the tests that matter are lead (and copper) at your tap, PFAS if your system's results or a nearby source raise a flag, and anything your report lists near its limit; routine compliance testing is the utility's job¹.

4. Pick a certified lab and method. Your state lists certified drinking-water labs². For PFAS, EPA Methods 533 and 537.1 are the validated drinking-water methods; other methods have not been evaluated by EPA, and “modified” methods are not standardized¹⁰. Skip cheap home lead kits³.

5. Read results with the right yardstick. For lead, EPA's health goal is zero. In the lead row of the report, look for how many sampled homes were above the action level of 15 parts per billion (ppb), which triggers steps by the utility when more than 10% of sampled taps exceed it; it is a system-level trigger, not a household safety line¹¹. A 2024 rule lowers the action level to 10 ppb, phased in from late 2027⁹. If your result is high, see lead in water and choosing a filter.

Can people read the report? Roy and colleagues evaluated a nationally representative sample of 30 CCRs released in 2011–2013 with Flesch-Kincaid readability tests. The reports were written at an 11th–14th grade level, well above the recommended 6th–7th grade level for public-health communication and comparable to the Harvard Law Review⁴. Iuliano and colleagues analyzed the content and communication quality of a nationally representative sample of 60 CCRs from water systems of different sizes and communities with different social vulnerability. Poorer-quality reports came more often from smaller systems and from those serving vulnerable communities, the same systems that are more likely to have drinking-water violations⁵. These are cross-sectional audits of report quality, not studies of what people understand or do. Their point for readers: a thin or confusing report is a reason to call the utility and test, not a sign that all is well.

Why test at your tap. Del Toral and colleagues compared stagnation sampling in 32 Chicago homes with lead service lines. Under the regulatory first-draw protocol, high lead was systematically missed. Sequential sampling found the highest levels within the lead service lines, with maximum values more than four times Chicago's compliance results, with large variability within and between homes and the highest results most often at sites where the service line had been disturbed⁸. The 2024 federal rule takes a related approach: for sites served by a lead service line, utilities must collect a paired first-liter and fifth-liter sample to capture water that sat in contact with the line, and sampling instructions may not tell residents to flush the tap or clean the aerator before the minimum six-hour stagnation period⁹. Your own certified test follows the same logic: follow the lab's instructions exactly, because the way you collect the sample can change the answer.

Home test kits. Kriss and colleagues evaluated at-home lead test kits: 16 brands of four types (binary color, binary strip, colorimetric vial and color strip). Twelve of the 16 brands had lead detection limits of 5–20 mg/L, far too high for drinking water. Binary strips detected dissolved lead at drinking-water-relevant levels but missed lead in particles, though household acids (lemon juice or vinegar) improved detection by dissolving some particles³. The study measured kit performance in the lab, not household outcomes, but it supports sending samples to a certified laboratory.

PFAS data and methods. UCMR 5 is a regulatory monitoring program, not a study: systems serving more than 10,000 people, those serving 3,300–10,000, and a random sample of 800 smaller systems measured 29 PFAS and lithium in a 12-month window between 2023 and 2025, and EPA says the results do not indicate compliance or noncompliance with the PFAS limits⁶. EPA Methods 533 and 537.1 together measure 29 PFAS in drinking water and are approved for UCMR 5¹⁰. Check EPA's current PFAS page for the limits that apply before interpreting a result.

Null and conflicting results. The CCR, EWG's database and your own tap can disagree without anyone being wrong: they measure different places, times and benchmarks. EWG's guidelines are intentionally stricter than legal limits⁷, and compliance sampling for lead uses a protocol that, in at least one city, missed the highest values⁸. We found no trial testing whether households that test their tap water have better health outcomes.

Bottom line (confidence 3 of 5). A two-step approach is sound: read your utility's CCR every year, then confirm lead and any local concerns at your own tap with a state-certified lab. The practical steps follow EPA guidance and sampling studies, but evidence that testing improves health outcomes is indirect.