What this article is: A plain-language guide to understanding the annual water quality report your city is required to send you. No product recommendations, no affiliate links — just the information you need to make sense of the numbers.
Every year, your water utility publishes a document called a Consumer Confidence Report (CCR). It lists every contaminant detected in your drinking water, the amounts found, and how those amounts compare to federal limits.
It’s one of the most useful documents a parent can read. It’s also one of the most confusing. The tables are full of abbreviations, the units are unfamiliar, and it’s not always clear what should concern you and what’s perfectly normal.
This guide will walk you through it, section by section, so you can read your own report with confidence.
Step 1: Find Your Report
The EPA requires every community water system serving more than 15 connections to publish a CCR by July 1 each year. Here’s how to find yours:
- Check your mailbox. Your utility may mail it to you, include it with a water bill, or send a postcard with a link to the online version.
- Search your utility’s website. Look for "water quality report," "CCR," or "annual drinking water report."
- Use the EPA’s search tool. Go to epa.gov/ccr and search by state and county to find your local system’s report.
On a Private Well?
If your home uses a private well, you won’t have a CCR. Private wells are not regulated by the EPA, and no one is testing your water for you. The CDC recommends testing well water at least once a year for bacteria, nitrates, and any contaminants common in your area. Your local health department can help you arrange a test.
Step 2: Understand the Key Terms
Before you look at the numbers, here are the abbreviations you’ll see on almost every CCR. Once you know these, the whole report clicks into place.
Maximum Contaminant Level
The legal limit — the highest level of a contaminant allowed in drinking water. Set by the EPA. If your water exceeds the MCL, your utility is required to notify you and take corrective action. MCLs balance health goals with what’s technically feasible for water systems to achieve.
Maximum Contaminant Level Goal
The health goal — the level at which there is no known or expected health risk, including a safety margin. MCLGs are not enforceable; they represent the ideal. For some contaminants (like lead), the MCLG is zero, meaning no amount is considered completely safe.
Action Level
Used specifically for lead and copper. Instead of an MCL, these contaminants have an action level — if more than 10% of tested homes exceed it, the water system must take steps to control corrosion. The action level for lead is 15 ppb.
Parts Per Billion / Million / Trillion
These are concentration units. Think of them as ratios: 1 ppm = 1 drop in 1 million drops. 1 ppb = 1 drop in 1 billion drops. 1 ppt = 1 drop in 1 trillion drops. Your CCR may also show these as μg/L (micrograms per liter, same as ppb) or mg/L (milligrams per liter, same as ppm).
Not Detected
The contaminant was tested for but not found above the lab’s detection limit. This is the best result you can see on your report.
Reported Values
Most CCRs show a range (lowest to highest detected) and an average or 90th percentile value. The range tells you the variation across different sampling points in your system. For lead and copper, the 90th percentile is the key number — it means 90% of tested sites were at or below that level.
Step 3: Read the Contaminant Table
The heart of your CCR is the contaminant table. Here’s what a typical one looks like (with simplified, fictional numbers for illustration):
| Contaminant | MCLG | MCL | Your Water | Violation? |
|---|---|---|---|---|
| Lead (ppb) | 0 | AL = 15 | 90th %ile: 4.2 | No |
| Copper (ppm) | 1.3 | AL = 1.3 | 90th %ile: 0.3 | No |
| Nitrate (ppm) | 10 | 10 | 1.8 | No |
| Total THMs (ppb) | N/A | 80 | 42 | No |
| Haloacetic Acids (ppb) | N/A | 60 | 28 | No |
| Fluoride (ppm) | 4 | 4 | 0.7 | No |
| Chlorine (ppm) | 4 | 4 | 1.2 | No |
In this example, every contaminant is below its legal limit. No violations. For most contaminants, this means your water meets federal safety standards.
But here’s what the table alone doesn’t tell you:
- Below the MCL does not always mean zero risk. For lead, the MCLG is 0 — meaning there is no level the EPA considers completely safe. A reading of 4.2 ppb is below the action level of 15, but it’s still lead in your water.
- MCLs are set for adults. Federal limits assume a 154-pound adult drinking about 2 liters of water per day over a lifetime. Babies drink far more water relative to their body weight, so the same concentration has a greater effect.
- Some contaminants may not appear at all. If your utility doesn’t test for something (because it’s not yet regulated), it won’t show up on your CCR. Many PFAS compounds, for example, were not required to be reported until recently.
Step 4: Know What to Watch For
Not every contaminant on your CCR warrants the same attention. Here are the ones that matter most for families, along with what the numbers mean in plain language.
Lead
Even below the action level, any detectable lead is worth paying attention to — especially if you have young children. Lead usually enters water from your home’s pipes, not from the water source itself, so your CCR may show low system-wide levels even if your specific faucet has higher levels. If lead is detected anywhere in your system’s testing, consider testing your own tap.
Nitrate
Particularly dangerous for infants under 6 months. At high levels, nitrate interferes with the blood’s ability to carry oxygen (methemoglobinemia, or "blue baby syndrome"). If your CCR shows nitrate above 5 ppm, keep an eye on it — it’s within legal limits but trending in a direction worth watching, especially if you have an infant.
PFAS (PFOA, PFOS, and others)
The EPA finalized its first-ever PFAS drinking water standards in 2024. If your CCR includes PFAS results, any detection is worth noting — the health goal is zero. Many water systems are still implementing testing, so if PFAS doesn’t appear on your report, it may mean it hasn’t been tested for yet, not that it’s absent.
Total Trihalomethanes (TTHMs)
Disinfection byproducts formed when chlorine reacts with organic matter in water. Levels above 40 ppb are common and legal but represent a higher byproduct load. Some research has associated elevated THMs with adverse pregnancy outcomes, though the evidence is not conclusive. If you’re pregnant and your levels are in the upper range, a basic carbon filter (even a Brita) can reduce THMs significantly.
Haloacetic Acids (HAA5)
Another category of disinfection byproducts. Like THMs, these form as a result of water treatment — a necessary tradeoff for keeping water free of harmful bacteria. They’re worth monitoring alongside THMs but are rarely an immediate concern at levels below the MCL.
Fluoride
Added intentionally by most utilities for dental health. The current recommended level is 0.7 ppm, reduced from 1.2 ppm in 2015. Levels above 2 ppm may cause dental fluorosis in children (cosmetic, not a safety emergency). Most systems run between 0.5–0.8 ppm, which is within the recommended range.
Step 5: Understand What Your CCR Does NOT Tell You
Your CCR is valuable, but it has real limitations. Understanding them will help you make better decisions.
It Tests at the Treatment Plant, Not Your Faucet
Your CCR reflects water quality in the distribution system — not at your specific tap. Contaminants like lead and copper can enter water from your home’s plumbing. Homes built before 1986 may have lead solder, and older homes may have lead service lines. The only way to know what’s at your faucet is to test at your faucet.
It Only Covers Regulated Contaminants
The EPA regulates about 90 contaminants, but there are thousands of chemicals that can end up in drinking water. Your CCR won’t include information on unregulated contaminants like microplastics, many pharmaceutical residues, or the hundreds of PFAS compounds beyond the handful now covered by federal rules.
It Uses Annual Averages
Some contaminants fluctuate throughout the year. Disinfection byproducts, for example, tend to spike in warmer months when water sources contain more organic matter. An annual average may mask seasonal highs. If your average is close to the MCL, peak levels may have exceeded it.
What to Do With What You’ve Learned
Once you’ve read your CCR, you’ll fall into one of three categories:
Your Water Looks Great
Most contaminants are low or not detected, no violations, lead is minimal. This is the reality for most families on municipal water. Use your water confidently. You can always test at the tap for extra assurance, but your CCR suggests your system is doing its job.
Some Numbers Are Worth Watching
Maybe your lead reading is low but detectable, or your THMs are in the mid-range, or PFAS hasn’t been tested yet. These aren’t emergencies, but they’re worth keeping an eye on. Consider testing your tap water directly, especially if you have an infant or are pregnant. Check next year’s CCR to see if the trend is moving up or down. You might also use our free water quality tool to see additional data for your ZIP code.
Something Looks Concerning
If your report shows a violation, lead above the action level, nitrates above 5 ppm with an infant in the home, or confirmed PFAS detection — take it seriously. Test your tap water at home, contact your utility for more information, and consider filtration for drinking and cooking water. Your pediatrician can also advise on whether your child should have a blood lead test.
A Quick Checklist for Parents
Here’s a simple process you can follow every year when your CCR arrives:
- Find the contaminant table. Skip the opening letter — go straight to the data.
- Check the "Violation" column. Any "Yes" entries mean your water exceeded federal limits. Read the explanation your utility provides.
- Look at lead. Find the 90th percentile value. Note whether it’s detectable, even if it’s below 15 ppb.
- Check nitrate. If you have a baby under 6 months, confirm it’s well below 10 ppm.
- Look for PFAS. If it’s listed, note any detections. If it’s not listed, it may not have been tested yet.
- Note disinfection byproducts (THMs and HAAs). Are they trending up from last year?
- Compare to last year’s report. Trends matter more than single readings. Increasing levels of any contaminant are worth watching.