How to Read Your Water Quality Report (And Why It Matters)

Every year, the water utility serving your home is required to send you a letter. Most people don't read it.

The Consumer Confidence Report — the annual drinking water quality report mandated by the EPA — is actually one of the most useful pieces of environmental health information you receive. It tells you what contaminants your utility tested for, what concentrations they found, and how those concentrations compare to the legal limits set by the Safe Drinking Water Act.

Most reports run to several pages and look, at first glance, like a compliance document written by lawyers. That's partly what they are. But buried inside is data that directly affects your health decisions — and learning to read it takes about 15 minutes once you know what to look for.

The first thing to understand is where to find yours. If you receive a physical copy in the mail, that's it. If not, the EPA maintains a database of CCRs at epa.gov/ccr — enter your ZIP code or water system name and you can pull up the most recent report. PollutionProfile's Water Quality feature links your address to your water system so you can access this context directly.

The most important distinction in your CCR — one that most readers miss entirely — is the difference between the Maximum Contaminant Level and the Maximum Contaminant Level Goal.

The MCL is the legal limit. If your utility's water exceeds an MCL, they are in violation of federal law and must notify you and take corrective action. It's enforceable.

The MCLG is the health-based goal — the level at which EPA believes there is no known or anticipated adverse effect on human health, with an adequate margin of safety. It is not enforceable.

For many contaminants, the MCL and MCLG are the same. But for carcinogens, the gap is often significant — and deliberately so. For lead, the MCLG is zero, because there is no safe level. The action level (the point at which utilities must take action) is 15 parts per billion. For arsenic, the MCLG is zero; the MCL is 10 ppb. For trihalomethanes — disinfection byproducts — the MCLG for several compounds is zero; the MCL is 80 ppb total.

What this means practically: a CCR showing all readings below MCLs is not the same as a CCR showing all readings near zero. A utility can be in full legal compliance while still delivering water that contains detectable levels of contaminants with no safe threshold. The EWG's Tap Water Database cross-references utility data against health guidelines rather than legal limits — and often finds a very different picture.

Not all contaminants appear with equal frequency in CCRs, and knowing which ones to look for first makes the reading exercise more useful.

Lead Every CCR must report lead and copper results. Look for the 90th percentile result — that's the level at which 90% of samples were below. The action level is 15 ppb; the MCLG is zero. Even if your utility reports compliance, lead exposure from home plumbing (especially in pre-1986 houses) may not be captured in utility-wide testing.

Nitrates Particularly relevant if you're in agricultural areas. The MCL is 10 mg/L. Elevated nitrates are associated with infant methemoglobinemia and emerging evidence for adult health effects.

PFAS Since 2024, the EPA has set the first-ever MCLs for six PFAS compounds. If your CCR is recent, it should include PFAS data. Check PFOA and PFOS specifically — the MCLs are 4 ng/L each, reflecting the low concentrations at which health effects have been observed.

Disinfection byproducts (DBPs) Total trihalomethanes (TTHMs) and haloacetic acids (HAAs) are the main ones. These form when chlorine reacts with organic matter in water. Look at the annual average and compare it to the MCL of 80 ppb for TTHMs.

Microbiological indicators Total coliform and E. coli results signal whether treatment is working. Any positive result for E. coli is a compliance violation.

Finding something concerning in your CCR doesn't mean your water is unsafe to drink today — but it does create a pathway for action.

If your utility has an MCL violation: They're required to notify you. Take the notification seriously — it specifies the contaminant, the level found, and what you should do (sometimes boil water, sometimes switch to bottled, sometimes nothing immediate). Check the EPA's enforcement records to understand whether this is a recurring issue or a one-off.

If readings are below MCLs but above health guidelines: This is the more common situation. The EWG database can show you which contaminants in your system exceed health goals even while meeting legal limits. For contaminants with zero MCLGs (lead, arsenic, PFAS), any detectable level warrants attention for vulnerable household members — infants, pregnant women, people with compromised immune systems.

Practical next steps by contaminant: • Lead: Test your own tap water independently (certified labs can do this for $20–50), use a filter certified to NSF/ANSI Standard 53 for lead reduction • PFAS: Reverse osmosis and activated carbon filters certified to NSF/ANSI Standard 58 are effective • Nitrates: Reverse osmosis or distillation • DBPs: Activated carbon filters reduce them significantly; letting water sit in an open pitcher for a few hours before drinking also helps

Enter your water system into PollutionProfile's Water Quality feature for a breakdown of your specific system's contaminant profile alongside guidance on which interventions are most relevant to your situation.