How to Read Your Water Quality Report (CCR)
A guide to understanding your city's Consumer Confidence Report and what the numbers mean.
What is a CCR?
Every water utility serving more than 15 connections must publish an annual Consumer Confidence Report (CCR), also called a Water Quality Report. This is required by the Safe Drinking Water Act. The CCR lists every contaminant detected in your water supply, the concentration found, the legal limit, the source of contamination, and any violations.
Your utility must deliver the CCR by July 1 each year. Most utilities mail it, email it, or post it online. You can also call your utility directly and request a copy. Many are available through the EPA's CCR search tool.
Key terms you will see
| Term | What it means |
|---|---|
| MCL (Maximum Contaminant Level) | The legal limit. Enforceable by the EPA. Based on health risk balanced against treatment feasibility and cost. |
| MCLG (Maximum Contaminant Level Goal) | The health-based goal, set purely on health with no consideration of cost. Often lower than the MCL. For carcinogens, the MCLG is typically zero. |
| Action Level | Used for lead and copper only. Not a health standard. Triggers utility action if exceeded at the 90th percentile of sampled homes. |
| 90th percentile | The value that 90% of samples fell below. Used for lead and copper. If the 90th percentile exceeds the action level, the utility must take corrective steps. |
| ppm / mg/L | Parts per million. Used for most contaminants. PPM and mg/L are the same thing for drinking water. |
| ppb / µg/L | Parts per billion. 1,000x smaller than PPM. Used for contaminants with very low limits (lead, PFAS, arsenic). |
| ppt / ng/L | Parts per trillion. 1,000x smaller than PPB. Used for PFAS compounds. |
| ND | Not detected. The contaminant was below the lab's detection limit. |
| Range | The low and high values detected across all sampling points. Your specific tap may fall anywhere in this range. |
What to look for first
Hardness
Often listed separately from regulated contaminants since it is not regulated. Measured in PPM or mg/L. Above 120 PPM is where a water softener starts making economic sense. Above 180 PPM, the impact on appliances, skin, and hair becomes significant. Convert PPM to GPG.
Lead and copper
Reported as a 90th percentile value, not an average. The lead action level is currently 15 ppb, dropping to 10 ppb in November 2027 under the LCRI. There is no safe level of lead exposure. If your CCR shows any lead detection, consider testing your own tap since lead varies dramatically by building.
PFAS
Newer CCRs may include PFAS data following the 2024 EPA rule. Any individual PFAS compound above 4 ppt exceeds the new standard. Many utilities are still in the process of testing and may not yet report PFAS. PFAS guide.
Disinfection byproducts (TTHM and HAA5)
Total trihalomethanes (TTHM) and haloacetic acids (HAA5) form when chlorine reacts with organic matter. MCLs are 80 ppb and 60 ppb respectively. These tend to be higher in summer, at the ends of distribution systems, and in systems using surface water. DBP guide.
Violations
Any CCR must list all violations that occurred during the reporting period. A violation means the utility exceeded a legal limit or failed to test. Even a single violation warrants attention. Repeated violations suggest systemic issues.
What the CCR does NOT tell you
The CCR reports water quality at the treatment plant and at sampling points in the distribution system. It does not reflect what comes out of your specific tap. Lead from your building's plumbing, copper from your pipes, and bacteria that may grow in your home's plumbing are not captured. The CCR also does not test for unregulated contaminants (microplastics, pharmaceuticals, many PFAS precursors).
For the most accurate picture of your water, start with the CCR for system-level data, then test your own tap for building-level concerns. Look up your city on CheckMyTap for a summary of the most important data points.
🧪 Recommended Test Kits
Affiliate links · We earn a commission at no cost to you
Check Your City's Water Data
See hardness, PFAS, lead, and chlorine levels for your city.