How to Read and Interpret Your Water Utility’s Drinking Water Quality Report (The Consumer Confidence Report)
Do you know where your drinking water comes from? A river? Lake? Aquifer? Are there contaminants in your drinking water? What are their levels, and should you be concerned?
Under the federal Safe Drinking Water Act, all US residents served year-round by a municipal water utility are entitled to information on the quality of their drinking water. (If you obtain your water from a private well, however, you will not receive a report; see instead the US Centers for Disease Control and Prevention’s Private Ground Water Wells website.)
The law requires water utilities communicate specific information to consumers in an annual report by July 1st of each year; the report may be delivered either by a hard copy mailing or electronic delivery. You must be informed about how you will receive the report. If you live in an apartment building or another rental unit, your landlord is required to let you know how to access the information. This report is known by various names such as a Consumer Confidence Report (CCR), “water quality report,” or “drinking water quality report.”
What the CCR Tells You1
The CCR provides a wealth of information, including:
- The SOURCE of your drinking water (e.g., lake, river, aquifer)
- The LEVELS of any contaminants2 found in your drinking water, and for comparison, the maximum level permitted by the EPA (the EPA’s health-based standard called the “maximum contaminant level”)
- The POTENTIAL health effects of any contaminant detected at levels higher than the health standard, and an accounting of the system’s actions to restore your drinking water to a safe level, and
- Phone numbers for ADDITIONAL SOURCES OF INFORMATION, including the water system and EPA’s Safe Drinking Water Hotline (800-426-4791).
Interpreting Contaminant Levels
It is easy to be confused by the many tables of numbers and other information in your CCR, so let’s walk through a representative table found in a 2013 water report from a US utility.
An Example of an Information Table on Regulated Substances in a Utility Distribution System
| Contaminant Name | Year | Average | Range Low – High |
Sample Size | Unit of Measure | MCL | MCLG | MCL Violation | Typical Sources |
|---|---|---|---|---|---|---|---|---|---|
| Arsenic | 2013 | 0.19 | 0.15 to 0.22 | 2 | ppb | 10 | 0 | No | Erosion of natural deposits; runoff from orchards; runoff from gladd and electonic production wastes |
| Barium | 2013 | 0.03 | 0.02 to 0.03 | 2 | ppm | 2 | 2 | No | Dischard of drilling wastes; discharge from metal refineries; erosion of natural deposits |
| Fluoride | 2013 | 0.74 | 0.74 to 0.75 | 2 | 990 | 4 | 4 | No | Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum factories |
| Nitrate | 2013 | 0.02 | 0.02 to 0.02 | 2 | ppm | 10 | 10 | No | Runoff from fertilizer use; leaching from septic tanks, sewage; erosiion of natural deposits |
The example table above lists 2013 levels of arsenic, barium, fluoride and nitrate detected in the utility’s drinking water in 2013.
Using nitrate (the last row) as an example, one can see in the column at the far right that the typical sources of nitrate in drinking water include: runoff from fertilizer use, leaching from septic tanks, sewage and erosion of natural deposits.
Based on what is presented in the table, for consumers served by this utility, nitrate in drinking water does not present a health issue. Why? Examine the columns labeled “Average” and “Range – Low to High,” and compare this to the columns labeled “MCL” and “MCLG”. Note that a level of 0.02 ppm is lower than 10 ppm. (A “ppm” or “part per million” is also referred to as milligram per liter, and is a way to express very low levels of substances in water.)
The table indicates that two samples (see the “sample size” column) of drinking water were analyzed for nitrate in 2013, and that the nitrate concentration ranged from 0.02 to 0.02 ppm, with an average of 0.02 ppm. EPA has set a Maximum Contaminant Level Goal (MCLG) of 10 ppm. The Maximum Contaminant Level (MCL) – the level EPA requires nitrate not exceed – is also 10 ppm. Because the nitrate levels found in this utility’s water system are lower than these maximum levels, nitrate is not considered a health risk for consumers of this utility’s drinking water.
The text box below provides for more information on the MCLG and the MCL.
The MCLG vs. the MCL
According to EPA, a Maximum Contaminant Level Goal (MCLG) is “the level of a contaminant in drinking water below which there is no known or expected risk to health.” MCLGs are set with a built-in margin of safety; utilities are not required to meet MCLGs. A Maximum Contaminant Level (MCL), on the other hand, is the highest level of a contaminant that is allowed in drinking water. An MCL for a given contaminant is set as close to its MCLG as feasible using the best available treatment technology and taking cost into consideration.
Your CCR is an important source of water quality information, a sort of “report card” for water utilities. The CCR can also provide customers with good information on projects the utility may be undertaking to improve the quality of the drinking water. For more information on CCRs, contact your water treatment facility (use contact information on your bill), or see the US Centers for Disease Control and Prevention webpage, Understanding Consumer Confidence Reports (CCR).
Steve Hubbs retired from water treatment operations at the Louisville Water Company in 2004. He was involved in the development of the first Drinking Water Disinfection Byproduct regulation in 1975-1979 and remains an active volunteer in the drinking water community today.
Linda Golodner is President Emeritus of the National Consumers League and Vice Chair of the Water Quality & Health Council.
1Based on the US Environmental Protection Agency website: Water: Consumer Confidence Report Rule, Basic Information. On line, available: http://water.epa.gov/lawsregs/rulesregs/sdwa/ccr/basicinformation.cfm
2EPA lists all regulated contaminants in US drinking water on its Water: Drinking Water Contaminants website at: http://water.epa.gov/drink/contaminants/index.cfm