Environmental Data Analysis
Making Sense of Your Annual Water Quality Report
Every year, public water utilities are required by law to send customers a Consumer Confidence Report (CCR), also called an Annual Water Quality Report. This document details what is in your drinking water, where it comes from, and how it compares to federal standards. Understanding this report empowers you to make informed decisions about your water.
What Is a Consumer Confidence Report?
The CCR is mandated by the 1996 amendments to the Safe Drinking Water Act. Water utilities serving more than 15 connections must deliver this report to customers by July 1 each year, covering the previous calendar year's testing results.
The report includes:
Finding Your Report
Water utilities must provide the CCR annually. You may receive it:
If you cannot locate your report, visit the EPA's Consumer Confidence Report page or contact your water utility directly. Our city water quality pages also summarize key findings from local water reports.
Key Terms You Need to Know
Before diving into the data, understand these essential terms:
Maximum Contaminant Level (MCL): The highest level of a contaminant legally allowed in drinking water. MCLs are set by the EPA and are enforceable standards.
Maximum Contaminant Level Goal (MCLG): The level of a contaminant below which there is no known health risk. MCLGs are not enforceable and are often set at zero for carcinogens.
Action Level (AL): The concentration that triggers required treatment or public notification. Used for lead and copper, which are measured at the tap.
Treatment Technique (TT): A required process intended to reduce contaminant levels. Used when measuring contamination is not practical.
Parts Per Million (ppm) or Milligrams Per Liter (mg/L): A common measurement unit. One ppm equals one milligram of contaminant per liter of water.
Parts Per Billion (ppb) or Micrograms Per Liter (ug/L): One thousand times smaller than ppm. Used for trace contaminants like lead and arsenic.
Parts Per Trillion (ppt) or Nanograms Per Liter (ng/L): One thousand times smaller than ppb. Used for extremely low-level contaminants like PFAS.
Range vs. Average: Reports often show both the range (lowest to highest detected) and average or 90th percentile values.
Understanding the Contaminant Tables
Your CCR will include one or more tables listing detected contaminants. Here is how to read them:
Contaminant Name: What was tested. Common categories include microbiological (bacteria), inorganic (metals, minerals), organic (chemicals), and disinfection byproducts.
Detected Level: The amount found in your water, with units (ppm, ppb, ppt).
MCL or AL: The regulatory limit for that contaminant.
MCLG: The health-based goal, often lower than the MCL.
Violation: Yes/No indicating whether the MCL was exceeded.
Likely Source: Where the contamination typically originates.
Example reading:
| Contaminant | Level Detected | MCL | MCLG | Violation |
|------------|----------------|-----|------|-----------|
| Lead (ppb) | 90th percentile: 8 | AL=15 | 0 | No |
| Arsenic (ppb) | 3 | 10 | 0 | No |
| Chlorine (ppm) | Range: 0.5-1.8 | 4 | 4 | No |
In this example, all contaminants are below regulatory limits, but lead has a MCLG of zero, meaning any detection represents some level of risk.
What the Numbers Really Mean
Contaminants Below MCL: Legally compliant, but may still warrant concern. For contaminants with MCLG of zero (lead, many carcinogens), any presence represents potential risk. Consider filtration for sensitive populations.
Contaminants at or Near MCL: Legal but at the edge of acceptable limits. Pay attention to trends and consider filtration, especially if you are pregnant, have children, or have health concerns.
Contaminants Exceeding MCL (Violations): Your utility must notify you and take corrective action. Follow any advisories provided. Consider filtration or alternative water sources until resolved.
Common Contaminants to Look For
When reviewing your CCR, pay special attention to these contaminants:
Lead: Check the 90th percentile value against the Action Level of 15 ppb. Remember there is no safe level of lead, and home plumbing can add lead after utility testing points.
PFAS (if reported): New EPA standards set MCLs at 4 ppt for PFOA and PFOS. Many utilities are still establishing baseline testing.
Disinfection Byproducts: Trihalomethanes (TTHMs) and haloacetic acids (HAA5) form when chlorine reacts with organic matter. MCLs are 80 ppb and 60 ppb respectively.
Nitrate: MCL is 10 ppm. Especially important for infant health as high levels can cause blue baby syndrome.
Arsenic: MCL is 10 ppb with MCLG of zero. A known carcinogen even at low levels.
Reading Between the Lines
Your CCR may not tell the whole story:
Testing frequency varies: Some contaminants are tested quarterly, others annually or less frequently. Results may not capture seasonal variations or recent changes.
Testing points matter: Utilities test at distribution system points, not your tap. Lead levels at your faucet may be higher due to home plumbing.
Not all contaminants are required: The CCR only includes regulated contaminants. Emerging concerns like microplastics, pharmaceuticals, and some PFAS compounds may not appear.
Average vs. peak levels: Averages can mask periodic spikes that exceeded limits.
Taking Action Based on Your Report
After reviewing your CCR:
If no violations and low levels: Your water meets federal standards. Consider additional testing at your tap if you have concerns about home plumbing, especially for lead.
If contaminants near MCL: Monitor future reports for trends. Consider point-of-use filtration for specific contaminants of concern.
If violations occurred: Follow utility guidance. Use filtered or bottled water for drinking and cooking until the issue is resolved. Check our guides for appropriate filtration.
If sensitive populations in home: Even compliant water may warrant additional filtration for pregnant women, infants, children, elderly, or immunocompromised individuals.
Questions to Ask Your Water Utility
After reviewing your CCR, consider contacting your utility with these questions:
Comparing to Our Data
Our city water quality pages provide additional context for your CCR data, including historical trends, comparisons to other cities, and specific contaminant analysis. Search for your city to see how your water compares.
Health Disclaimer: This information is provided for educational purposes and does not constitute medical advice. While this guide helps you understand water quality reports, specific health decisions should be made in consultation with healthcare providers. For official EPA guidance on drinking water standards, visit epa.gov/ground-water-and-drinking-water. Water quality can change, so review current reports and contact your utility for the latest information.
Topics Covered
Frequently Asked Questions
When should I receive my Consumer Confidence Report?
Water utilities must deliver the CCR to customers by July 1 each year, covering the previous calendar year. Some utilities mail physical copies while others provide electronic access. If you do not receive a report, contact your water utility or check their website.
What if my water has contaminants below the MCL but above zero?
Water meeting MCL standards is legally compliant, but some contaminants like lead have health goals (MCLGs) of zero. Any presence represents some level of risk. For sensitive populations or contaminants of particular concern, consider additional testing at your tap and point-of-use filtration.
Does my CCR show what is in my tap water specifically?
Not exactly. Utilities test at distribution points, not individual homes. Contaminants like lead can enter water from your home plumbing after it leaves the distribution system. For accurate tap water assessment, especially for lead, additional testing at your faucet is recommended.
Why are some contaminants not listed in my CCR?
The CCR only includes contaminants that are detected. If a contaminant was tested for but not found, it may not appear. Additionally, some emerging contaminants like microplastics are not yet regulated, so they will not appear in standard reports even if present.
What does it mean if my water had a violation?
A violation means a contaminant exceeded the legal limit or required treatment was not performed. Your utility must notify you and take corrective action. Follow any advisories provided, consider using filtered or bottled water until resolved, and monitor subsequent reports for resolution.
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