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Garrett County Government
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General Laboratory Information

Why Test Your Water?

If you´ve had your water tested, you probably did so to find out if it is safe to drink. Even if your water tastes, smells and looks fine, water testing is necessary because many contaminants have no obvious odors or tastes. In other cases, where a water quality problem is obvious, testing can determine the exact concentration of the pollutant to assist in determining the best solution to the problem.
Water testing is especially necessary if your house is served by a private water system, because many of these systems have water quality problems. Private water systems include drilled wells, dug wells, springs, or cisterns that serve an individual home. There are no regulations of laws that require water testing, system maintenance, or water treatment on private systems. Rather, owners must voluntarily test for contaminants and correct any problems to provide safe drinking water. It is recommended that homeowners maintain their water quality to the same standards required by law for public water supplies.
Always have your water collected by a certified sampler and tested by a certified water-testing laboratory. The Maryland Department of the Environment certifies individuals for the collection of drinking water samples and water testing laboratories in Maryland. The Garrett County Public Utilities Laboratory´s certification number is G-1035. The laboratory is currently certified to collect and analyze drinking water samples for Total Coliform and E.Coli bacteria.

What are Drinking Water Standards?

Drinking water standards give the level of a pollutant that is acceptable in drinking water. The U.S. Environmental Protection Agency (EPA) sets these standards. The EPA sets standards for contaminants that are known to occur in water, are detectable in water and cause a health or aesthetic problem in water. The Maryland Department of the Environment enforces the standards on public water systems, but not on private water supplies. The Garrett County Environmental Health Department is responsible for the enforcement of local standards on newly constructed wells in Garrett County.

Understanding Your Water Test Report

All drinking water test results and standards have a unit associated with them. These units give the amount of the pollutant per unit of water. The most common unit is milligram per liter (mg/L), which expresses the milligrams of a pollutant in every liter of water. Milligrams per liter can also be expressed as parts per million (ppm). Some contaminants, such as Arsenic, that can be measured in very small quantities are reported in microgram per liter (Ug/L). Micrograms per liter can also be expressed as parts per billion (ppb). These units express the very small concentration of pollutants that occur in water. The following examples illustrate just how small these units really are.
  • One milligram per liter (mg/L) or part per million (ppm) corresponds to one minute in two years or a single penny in $10,000.
  • One Microgram per liter (Ug/L) or part per billion (ppb) corresponds to one minute in 2,000 years or a single penny in $10,000,000.

Bacteria Pollutants

Many different kinds of bacteria may be present in a water supply. Some bacteria are disease causing but many are not. The tests discussed below are specific bacteria test that are used to determine whether disease-causing organisms may be present in water.

Coliform Bacteria:

Coliform bacteria are a large group of bacteria that occur throughout the environment. They are used as an indicator organism to indicate the potential for disease-causing bacteria to be present in water. In other words, if coliform bacteria are present, it is presumed that a pathway exists between the bacteria source and the water supply and that disease-causing organisms may use this pathway to enter the water supply. Coliform bacteria occur frequently in private water systems, usually from contamination by surface runoff or from human or animal wastes.
Consuming water with coliform bacteria present may cause gastrointestinal illnesses, fever, and other flu-like symptoms. Therefore, the drinking water standard requires that no coliform bacteria be present in drinking water supplies. Coliform bacteria persist in water longer than most disease-causing bacteria. This leads to the assumption the water supply is microbiologically safe to drink if no coliform bacteria are detected in the water.
Since no coliform bacteria may be present in a drinking water supply, the Deep Creek Lake Laboratory normally expresses results from coliform tests as "Present" (P), or "Absent" (A). "Present" indicates that at least one bacterium was present in the 100 milliliters of sample collected. Most coliform bacteria do not cause disease, but the greater their number the greater the likelihood that disease-causing bacteria may be present. Therefore, The Deep Creek Lake Laboratory can also enumerate the bacteria results. In this case the results will be expressed as "MPN", which stands for Most Probable Number. This simply means that a statistical relationship was used to estimate the number of bacteria in your sample.

E. Coli:

The Deep Creek Lake Laboratory is also certified to analyze for E. Coli in drinking water supplies. E. Coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. A positive E. Coli result is a strong indication that human sewage or animal waste has contaminated the water. This test can also be run as the "Present / Absent" method or by the "MPN" method. Hundreds of strains of E. Coli exist. Although most are harmless and live in the intestines of healthy humans and animals, a few can produce a powerful toxin that causes serve illness and even death.

Need More Information

Do you still have questions? You can contact the Deep Creek Lake Laboratory at 301-387-6162. In addition, there are numerous sources of both written and online information related to drinking water and interpreting water test results. Listed below are some locations that may be helpful for finding more information on drinking water and interpreting water test results.
U.S. Environmental Protection Agency
Safe Drinking Water Hotline
Office of Groundwater and Drinking Water
U.S. EPA Drinking Water and Health
U.S. Department of Agriculture-National Extension Water Quality Database
The Maryland Department of the Environment
Water Supply Program
Garrett County Health Department
The Department of Health and Mental Hygiene