Extension and Ag Research News


Here's How to Interpret Annual Community Water Reports

An NDSU Extension water quality associate offers tips on reading a community water quality report.

If you use a community water source, you probably receive a water quality report.

The Safe Drinking Water Act requires community water suppliers to provide their customers with the report annually.

""This is an opportunity to learn about the source and quality of your drinking water,"" says Roxanne Johnson, North Dakota State University Extension Service water quality associate. ""The Consumer Confidence Report will inform you of potential contaminants, their levels and the possible source of contaminants in your water supply.""

To understand the report, you should be familiar with the terminology water systems use, according to Johnson. The units of measurement may vary, depending on the contaminant being measured. The following are some unit abbreviations you may see in the report:

  • mg/L - Milligrams per liter. Micrograms per liter (ug/L) is used for smaller amounts. One milligram per liter divided by 1,000 is equal to 1 microgram per liter.
  • ppm - Parts per million or milligrams per liter. 1mg/L = 1 ppm. The reports may use parts per billion (ppb) for very small amounts. One part per million divided by 1,000 is equal to 1 part per billion.
  • MFL - Million fibers per liter. It's used to measure asbestos, which exists as tiny fibers.
  • NTU - Nephelometric turbidity units. It measures the turbidity, or clarity, of the water.
  • pCi/L - Pico curies per liter. It's a measurement of radioactivity used for contaminants such as radium, uranium and radon. They emit radioactive waves the body may absorb.
  • gpg - Grains per gallon refers to the hardness of water. For example, more than 10 gpg is very hard water; less than 1 gpg is very soft water. This also can be reported in mg/L.

Here are some abbreviations for terms you may find in the report:

  • AL - action level. It's the level of a harmful or toxic substance/activity requiring treatment.
  • MCL - maximum contaminant level. This is the maximum permissible concentration of a contaminant in public water supplies. The Environmental Protection Agency sets an MCL after considering health effects, as well as the feasibility and cost of analysis and treatment of the regulated contaminant.
  • MCLG - maximum contaminant level goal. This preliminary standard is based entirely on health effects the EPA uses to establish a contaminant's MCL. For example, the MCLG is zero for a chemical believed to cause cancer.
  • NA - not analyzed. It can mean the source water has been deemed nonvulnerable to a specific contaminant or that testing was not required.
  • ND - not detected. The contaminant in question wasn't found in the water sample.
  • TT - treatment technique. This includes procedures community water suppliers must follow to ensure a contaminant in their drinking water supplies is controlled.

Most water quality reports contain several columns of information. The following is a brief description of some of them:

  • Detected substance - It's a contaminant that was detected in the water and is being analyzed.
  • Date of analysis - This is the date when a substance was found in the water.
  • Level found in your city water - This is the amount of contaminant found in your drinking supply. It may be reported as an average for the year or as a range.
  • Range of detections - It's a range of contaminant amounts found in the sample.
  • Typical source in drinking water - This is the potential source of the contaminant, such as an additive or particular form of business, or whether it's naturally present.

Johnson suggests you compare the level of a particular contaminant shown in the ""amount detected"" column against the level in the ""MCL"" column. This will help you determine whether a particular contaminant is present in your drinking water at a level that is near or exceeds federal or state guidelines.

Also compare the ""amount detected"" in your water supply against 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 required to keep contaminant levels below the MCL level, but not the MCLG level.

If you have questions about your community water report, contact your water supplier. For more information on interpreting your water test and options for home water treatment systems, visit the NDSU Extension Service's Web site at http://www.ag.ndsu.nodak.edu/pesth2o.htm.

Agriculture Communication

Source:Roxanne Johnson, (701) 231-8926, roxanne.m.johnson@ndsu.edu
Editor:Ellen Crawford, (701) 231-5391, ellen.crawford@ndsu.edu
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