Testing

How to read your annual water quality report

Every community water system in the country publishes one of these each year. Almost nobody reads it, largely because the table is written for regulators.

Where to find it

Most systems mail it or include it with a bill; many now send a link instead. Failing that, your utility's website will have it, usually under a heading like water quality. Search for your utility's name with the phrase Consumer Confidence Report and the year.

If you rent, the report goes to the account holder, which may be your landlord. You are entitled to it, and the utility will provide it on request.

Reading the table

The contaminant table is the core of the report and it is written in regulatory shorthand. Five columns do the work.

Two habits make the table far more informative.

Read the range, not just the average. A system averaging well under a limit but with a maximum close to it has months that look very different from its annual figure. Compliance is generally judged on averages, so a high individual result can be entirely lawful and still worth knowing about.

Compare the detected level to the MCLG, not only the MCL. The gap between the two is the difference between what is legally permitted and what health science would prefer. For lead the goal is zero, so any detection sits above it.

The four things worth checking first

1. Violations. The report must disclose any violation during the year, along with what was done about it. This is usually a short section and it is the first thing to read.
2. Lead. Reported as the 90th percentile of sampled homes, which means 10% of sampled homes were above that figure. It describes the system, not your building — the service line to your own property is what decides your exposure.
3. Disinfection by-products. Total trihalomethanes, limit 0.080 mg/L, and haloacetic acids, limit 0.060 mg/L. A system running consistently near either is managing a genuine trade-off worth understanding.
4. Your source water. Stated near the top: surface water, groundwater, or a blend. It determines which contaminants are plausible in the first place.
5. Fluoride. Listed if detected at any level, and the report distinguishes added fluoride from natural. Two different numbers govern it and they do different jobs.

What the report will not tell you

• Your tap. Samples are taken at the entry point to the distribution system and, for lead, at a small sample of homes. Your own plumbing is not represented.
• Unregulated contaminants. Most systems report only what they are required to. PFAS results generally appear only where a state requires it or the system chose to disclose.
• Anything below the reporting limit. A blank is not a zero. It means not measurable by the method used.
• This year. The report covers the previous calendar year and can be up to eighteen months behind current conditions.

How it fits with the federal PFAS data

The two sources are complementary and neither replaces the other.

Our lookup covers 30 PFAS-related substances measured under a national program that ran from 2023 to 2025, at 10,313 systems. Your annual report covers roughly 90 regulated contaminants at your system, updated every year, including everything the PFAS program did not measure.

Read together they give you most of what is knowable about a municipal supply without commissioning your own test. The remaining gap — what happens between the main and your kitchen — can only be closed by testing at your own tap.