How to Read a Water Quality Report
Your complete guide to understanding Consumer Confidence Reports (CCR) and what they mean for your water safety
What is a Consumer Confidence Report?
Every community water system serving more than 15 service connections must deliver an annual Consumer Confidence Report (CCR) to its customers by July 1st each year. This report is your right under the Safe Drinking Water Act.
What's Included in a CCR:
- ✓Information about your water source
- ✓List of all contaminants detected in your water
- ✓Comparison of contaminant levels to EPA standards
- ✓Treatment methods used to purify water
- ✓Any violations of drinking water standards
- ✓Contact information for your water utility
Understanding Key Terms
MCL (Maximum Contaminant Level)
The highest level of a contaminant allowed in drinking water. Set by the EPA based on health risks and treatment feasibility. Water systems must keep contaminant levels below MCLs.
MCLG (Maximum Contaminant Level Goal)
The ideal level of a contaminant with no known health risks. Often set at zero for carcinogens. MCLGs are goals, not enforceable limits. The enforceable limit is the MCL.
Action Level (AL)
The concentration of lead or copper which triggers treatment requirements. If 90% of homes test below the AL, the system is in compliance. Used for lead (15 ppb) and copper (1.3 ppm).
ND (Not Detected)
The contaminant was either not present or below the laboratory detection limit. This is generally good - it means the contaminant is absent or at extremely low levels.
TT (Treatment Technique)
A required process to reduce contaminant levels. Used when it's not feasible to measure the contaminant directly. Examples include filtration for Cryptosporidium.
ppb / ppm / ppt
Parts per billion, parts per million, parts per trillion. These measure concentration. 1 ppb = 1 drop in a swimming pool. 1 ppm = 1 drop in a bathtub. 1 ppt = 1 drop in 20 Olympic pools.
Reading the Contaminant Data Table
The heart of every CCR is the contaminant data table. Here's how to interpret it:
Example Table Entry:
| Contaminant | Level Found | MCL | MCLG | Source |
|---|---|---|---|---|
| TTHMs | 45 ppb | 80 ppb | 0 ppb | Chlorination byproduct |
What This Means:
- 1.Level Found (45 ppb): The actual amount detected in your water
- 2.MCL (80 ppb): The legal limit - your water is 56% of the maximum allowed
- 3.MCLG (0 ppb): The ideal level (often zero for carcinogens)
- 4.Source: Where the contaminant comes from
What to Look For in Your Report
Good Signs
- • All contaminants below MCLs
- • Many readings show "ND" (Not Detected)
- • No violations reported
- • Detected levels are low percentages of MCLs
- • Water source is protected (e.g., deep aquifer, protected watershed)
Watch For
- • Contaminants approaching 50% or more of MCL
- • Lead levels above 5 ppb (especially if you have children)
- • Disinfection byproducts (TTHMs, HAA5) above 50% of MCL
- • Nitrates above 5 ppm (especially for infants)
- • Multiple contaminants at elevated levels
Red Flags
- • Any contaminant exceeding MCL
- • Violations listed in the report
- • E. coli or coliform bacteria detected
- • Boil water advisories or health alerts
- • Missing or incomplete data for required contaminants
- • Nitrate levels approaching 10 ppm
Common Contaminants to Understand
Lead
Source: Leaches from pipes and plumbing fixtures, especially in older homes.Health Effects: Developmental delays in children, high blood pressure in adults.Action Level: 15 ppb.
Disinfection Byproducts (TTHMs/HAA5)
Source: Formed when chlorine reacts with organic matter in water.Health Effects: Potential cancer risk with long-term exposure.MCLs: 80 ppb (TTHMs), 60 ppb (HAA5).
Nitrates
Source: Agricultural runoff, septic systems, fertilizers.Health Effects: Can cause blue baby syndrome in infants.MCL: 10 ppm.
Arsenic
Source: Naturally occurring in groundwater, mining, industrial waste.Health Effects: Cancer risk, cardiovascular disease.MCL: 10 ppb.
PFAS (Forever Chemicals)
Source: Industrial discharge, firefighting foam, consumer products.Health Effects: Cancer, thyroid disease, immune system effects.EPA Limits: Vary by state; federal standards being implemented.
What to Do After Reading Your Report
If Your Water Meets Standards:
- ✓Your water is legally safe to drink
- ✓Consider a filter for taste improvement or extra protection
- ✓Test your home's water if you live in an older building (for lead)
- ✓Review your report annually to track changes
If You Have Concerns:
- 1.Contact your water utility with specific questions
- 2.Get your home's water tested by a certified laboratory
- 3.Install NSF-certified filters for specific contaminants
- 4.If violations exist, attend public meetings and voice concerns
Frequently Asked Questions
What is a Consumer Confidence Report?
A Consumer Confidence Report (CCR) is an annual water quality report required by the EPA that water utilities must provide to customers. It includes information about detected contaminants, their levels, EPA limits, source water, and treatment methods.
What does MCL mean in water quality reports?
MCL stands for Maximum Contaminant Level. It is the highest level of a contaminant allowed in drinking water, set by the EPA based on health risks and treatment feasibility. Water systems must keep contaminant levels below MCLs.
What does ND mean in water test results?
ND means Not Detected. It indicates the contaminant was either not present or was below the laboratory detection limit. This is generally a good sign, showing the contaminant is absent or at extremely low levels.
How often should I review my water quality report?
Review your CCR every year when it arrives (by July 1st). Compare year-to-year to track changes in water quality. If you notice concerning trends or new violations, contact your water utility for more information.