Understanding Consumer Confidence Reports (CCRs)

U.S. Environmental Protection Agency (EPA) requires most community water systems to provide customers with an annual water quality report. Also known as Consumer Confidence Reports or CCRs, these reports provide residents with detailed information about the quality of their drinking water supply during the past year.

Most homeowners will automatically receive a copy of the report each year. People living in apartments or condominiums may not receive a copy directly, but can still access this information on their community's website or by calling the local water department.

EPA requires that each report contains the following information about the community's drinking water supply:

  • The source of the water. Possible sources may include wells, rivers, lakes and reservoirs.
  • The levels of any contaminants found in the local drinking water. These may be reported as an average level or as a range.
  • The likely source of any detected contaminants and the susceptibility of a water supply to potential contamination.
  • The EPA maximum contaminant levels (MCL). These are the levels at which certain contaminants are considered to be potentially harmful.
  • Any violation of drinking water-related rules, including a violation of the MCL in which a contaminant exceeds the allowable limit. The report must also include an explanation of the water system's actions to restore safe drinking water.
  • An educational statement regarding Cryptosporidium and the need for certain vulnerable populations to avoid exposure to these organisms.

Not all items in these reports refer to harmful contaminants. Some issues do not pose a health risk, but can affect the appearance or taste of the water (such as iron, chlorine, sediment, the amount of hardness, sodium and sulfates).

Understanding Your Report

CCRs can look a little technical, but they are actually fairly easy to read once you know what to look for. Here are some terms you should know when reviewing your CCR:

Units of Measurement

There are several ways to measure the concentration, or amount, of a contaminant that is present in water. Common units of measurement that you are likely to see on your CCR include:

mg/L Milligrams per liter is one of the most common units of measurement used to report contaminants. One mg/L is equal to 4.5 drops in a 55-gallon barrel of water.
µg/L For smaller amounts, micrograms per liter is frequently used. One milligram per liter divided by 1,000 is equal to one microgram per liter. One ug/L equals about 4.5 drops in a 60,000-gallon swimming pool.
ppm Parts per million is the same as milligrams per liter.
1 mg/L = 1 ppm
ppb Parts per billion is the same as µg/L. 1 ppb = 1 µg/L. One part per million divided by 1,000 is equal to one part per billion.
pCi/L Pico curies per liter is used to measure contaminants such as radium, uranium and radon. These contaminants emit radioactive waves that may be absorbed by the body.
gpg Grains per gallon refers to the hardness concentration of water. Very hard water has more than ten grains per gallon, and very soft water has less than one grain per gallon. Hardness can also be reported in mg/L.
1 gpg = 17.1 mg/L


AL Action level refers to the concentration of lead and/or copper in tap water that may affect local water treatment decisions. Unlike MCLs, AL violations do not require public notifications. Most high levels of lead and copper are due to household pipes and faucets.
MCL Maximum contaminant level is the maximum level of a contaminant allowed in public drinking water supplies. Water suppliers are required to notify residents when an MCL is exceeded.
MCLG Maximum contaminant level goal is the level of a contaminant in drinking water at which there is no known or anticipated health threat to a person who consumes the water.
NA Not analyzed means that the source water has been deemed non-vulnerable to a specific contaminant or that testing was not required.
ND Not detected means that none of the contaminant was found in the water sample. Water analysis equipment has detection limits, which refer to the smallest amount of a contaminant that the equipment is capable of detecting.
TT Treatment technique refers to the set of procedures that public water suppliers must follow to ensure that a contaminant is controlled in their drinking water supplies. refers to the set of procedures that public water suppliers must follow to ensure that a contaminant is controlled in their drinking water supplies.

Interpreting the Results of Your Report

Water quality reports contain several columns of information. The key columns to review include:

  • Contaminant or parameter name — Refers to the particular substance being analyzed for in the water, such as lead.
  • Unit — Refers to the unit of measurement in which a particular contaminant is being reported, such as parts per million (ppm).
  • MCLG — Maximum contaminant level goal. Indicates the level of a contaminant in drinking water below which there is no known or expected risk to health.
  • MCL — Maximum contaminant level. Indicates the highest level of contaminant allowed in drinking water.
  • Amount detected — The level at which the contaminant was detected in your water supply. The amount will be reported either as an average for the year or as a range.
  • Violation — A yes in this column indicates your community had a contaminant present in the water that exceeded an MCL.
  • Source — This column indicates the potential source of a particular contaminant, such as naturally present, an additive or the result of contamination from a particular form of business.

For each contaminant, compare the level shown in the "amount detected" column to the level shown in the "MCL" column. This helps you determine if a particular contaminant is present in your drinking water at a level that is near or exceeds federal or state guidelines.

You can also compare the "amount detected" in your water supply to the level shown in the "MCLG" column. Keep in mind that the MCLG level is simply a target goal, not a requirement. Water utilities are currently required to keep contaminant levels below the MCL level, but not the MCLG level.

Contaminant or Taste/Odor/Color Issues

Ultimately, CCRs help you identify what contaminants, if any, are present in your tap water supply and how these contaminants may affect your health. If a contaminant is present at a level that is of concern or if your water has an undesirable taste, odor or color, you can take any number of actions. For many people, the first step might be to purchase a water filter or water treatment system. However, no single system can protect against all impurities, so it's important to do your homework before selecting a water treatment system.

Questions About the CCR Reports

Your local water supplier can answer questions and provide you with information on local water quality conditions, the type of treatment processes used and how often the water supply is analyzed for specific contaminants.

Questions About Government Regulations of Water Quality?

The U.S. EPA's safe drinking water hotline at 1-800-426-4791 answers questions regarding the development of the MCL and MCLG levels shown on your report. The hotline staff can answer questions about federal drinking water standards and provide general information on water quality in the United States.

The NSF Consumer Affairs Office also addresses questions on many water quality topics. You can contact our Consumer Information Office via our toll-free consumer hotline at 1-800-673-8010 or send an email, info@nsf.org.

Selecting a Water Treatment System

If your water has a taste, odor or color issue, or you are concerned about the presence of a particular contaminant and are considering the use of a water filter or home water treatment device, you can use the NSF Contaminant Guide to locate a list of products certified to address that issue.

NSF evaluates hundreds of brands of water treatment devices each year to ensure they meet standards for design and performance. You can be confident that home water treatment devices that carry NSF certification reduce the contaminants as claimed by the manufacturer, without adding harmful levels of impurities into the water being treated.