Understanding Your Water Quality Report
Your water quality report -- officially called a Consumer Confidence Report (CCR) -- is designed to tell you exactly what is in your drinking water. But the acronyms, measurement units, and regulatory jargon make it feel impenetrable. This guide translates it into plain English so you can assess your water quality in about 5 minutes.
For a comprehensive deep-dive covering every section of a CCR in detail, see our complete guide to reading water quality reports. This article focuses on the essential numbers, what they mean for your health, and what action to take if something looks concerning.
What Is a Consumer Confidence Report (CCR)?
Every community water system in the United States must publish a CCR annually by July 1st, as required by the Safe Drinking Water Act. The report covers all contaminant testing results from the previous calendar year.
Your CCR tells you:
- What contaminants were tested for
- The levels detected in your water
- How those levels compare to federal limits (MCLs)
- Where your water comes from (surface water, groundwater, or both)
- Any violations or health advisories during the reporting period
Where to find it: Your utility either mails it or publishes it online. You can also search the EPA CCR search tool by utility name or state. For instant water quality data without waiting for the annual report, check your water by zip code on our database.
The Key Numbers You Need to Understand
MCL: Maximum Contaminant Level
The MCL is the legal limit -- the highest concentration of a contaminant allowed in drinking water. If a test result is at or below the MCL, your water is in compliance with federal standards. If it exceeds the MCL, your utility must take corrective action and notify customers.
MCLs are set by the EPA and reflect a balance between health protection, treatment technology, and cost. They are not pure health thresholds -- they consider what is achievable and affordable for water systems to implement.
MCLG: Maximum Contaminant Level Goal
The MCLG is the health target -- the level at which no adverse health effects are expected, even after a lifetime of daily exposure. MCLGs are based purely on health science, with no consideration of cost or feasibility.
The gap between MCL and MCLG matters. For many contaminants, the MCL is higher than the MCLG because reducing contamination to the health goal is not currently feasible. For known carcinogens (including certain PFAS compounds) and for lead, the MCLG is set at zero -- meaning any detection carries some theoretical health risk, even though the legal limit allows small amounts.
ppb and ppm: Units of Measurement
- ppm (parts per million) = milligrams per liter (mg/L). One ppm is roughly one drop of ink in a 13-gallon fish tank.
- ppb (parts per billion) = micrograms per liter (ug/L). One ppb is one drop of water in a swimming pool. There are 1,000 ppb in 1 ppm.
- ppt (parts per trillion) = nanograms per liter. Used for ultra-trace contaminants like PFAS. There are 1,000 ppt in 1 ppb.
Your CCR may use any of these units depending on the contaminant. Lead is typically reported in ppb, chlorine in ppm, and PFAS in ppt.
Action Level (AL)
Used specifically for lead and copper under the Lead and Copper Rule. The action level is not a health standard -- it is a trigger for additional treatment requirements. When more than 10% of sampled homes exceed the action level, the utility must take corrective steps.
- Lead action level: 15 ppb (0.015 mg/L) currently. Under the revised Lead and Copper Rule Improvements (LCRI), the action level drops to 10 ppb starting in 2027.
- Copper action level: 1.3 ppm (1.3 mg/L).
ND: Non-Detect
ND means the contaminant was not found at detectable levels given the laboratory's equipment sensitivity. This does not necessarily mean zero -- it means the concentration is below the detection limit, which varies by contaminant and testing method. Detection limits are listed in your CCR's methodology section.
Common Contaminants and What They Mean
Here are the contaminants most frequently reported in CCRs and what to know about each:
| Contaminant | Source | Federal Limit | What to Know |
|---|---|---|---|
| Lead | Old pipes, solder, fixtures | AL: 15 ppb (dropping to 10 ppb in 2027) | No safe level for children. MCLG is 0. Test at the tap, not the source. |
| Chlorine / Chloramine | Added for disinfection | MRDL: 4 ppm | Safe at regulated levels. Causes taste and odor. Filter with activated carbon if bothersome. |
| PFAS (PFOS, PFOA) | Industrial contamination | MCL: 4 ppt each (2024 rule) | Serious health concern. Persistent "forever chemicals." Very low limit reflects toxicity. |
| Nitrate | Agriculture runoff, fertilizer | MCL: 10 ppm (as nitrogen) | Dangerous for infants under 6 months (blue baby syndrome). Safe for adults at regulated levels. |
| Total Trihalomethanes (TTHMs) | Disinfection byproducts | MCL: 80 ppb (0.080 mg/L) | Formed when chlorine reacts with organic matter. Linked to cancer risk at elevated levels. |
| Hardness | Naturally occurring minerals | Not regulated | Not a health risk. Measured in GPG or ppm. Causes scale on fixtures and appliances. See our water softener cost guide if levels are above 7 GPG. |
| Copper | Plumbing corrosion | AL: 1.3 ppm | Usually from household pipes, not the water source. Can cause GI issues at high levels. |
| Fluoride | Added for dental health / natural | MCL: 4 ppm | Health advisory at 2 ppm. Most systems add 0.7 ppm for dental benefit. |
Red Flags: When to Take Action
Use this decision framework when reviewing your CCR or home test results:
Any contaminant above its MCL: Contact your water utility immediately to confirm results and learn what corrective action is planned. Your utility is legally required to address violations. In the meantime, consider a certified water filter for the specific contaminant.
Lead detected above 15 ppb (or any detection in homes with young children): Lead has no safe level for children. Run your tap for 30 seconds before drinking to flush standing water from lead pipes. Install a certified lead-removing filter. If your home was built before 1986, it may have lead solder or service lines.
PFAS detected at any level: The 2024 EPA rule set MCLs at 4 ppt for PFOS and PFOA individually, but health organizations including EWG suggest that no level of PFAS exposure is truly safe. Consider a reverse osmosis or activated carbon filter certified for PFAS removal. Check your area's PFAS levels.
Multiple contaminants above their MCLGs but below MCLs: Your water is legally compliant but may carry elevated health risk, especially with long-term exposure. This is common -- many water systems meet legal limits while exceeding health goals. Review your specific contaminants at tapwaterdata.com/zip for guidance on which filters address your situation.
Hardness above 7 GPG: Not a health concern, but causes scale damage to plumbing and appliances. A water softener prevents buildup and extends appliance life. See our water softener cost guide for pricing and recommendations.
What to Do If Your Water Has Issues
Step 1: Check Your Current Water Quality
Look up your water quality by zip code for the latest available data on contaminants in your water supply. This is faster than waiting for the annual CCR and includes contaminants compared against both EPA legal limits and stricter health guidelines.
Step 2: Confirm with a Home Water Test
If your CCR or our database shows contaminants of concern, a home water test kit ($20-$50) or certified lab test ($100-$300) can confirm levels at your specific tap. This is especially important for lead, which varies by household based on the age and material of service lines and interior plumbing.
Step 3: Choose a Certified Filter
For confirmed contamination, select a water filter certified to NSF/ANSI standards for your specific contaminants. Not all filters remove all contaminants -- a carbon filter removes chlorine and some PFAS but not lead, while a reverse osmosis system removes nearly everything. Browse our water filter guides for recommendations matched to specific contaminants.
Step 4: Address Hardness Separately
Water hardness is not a health issue but is the most common water quality complaint. If your water tests above 7 GPG, a water softener prevents scale damage and reduces soap usage. Our water softener cost guide covers pricing from $800-$3,000 for the unit, and our best water softener reviews compare top-rated systems.