Water Contamination

Contaminants in Your Drinking Water
To assure a safe water supply, municipal (city) water systems are required to test their water on a regular basis. However if you have a private well it's up to you to make sure your water is free of contaminants. For a small fee, the Scott County Environmental Health Department sells a water test kit that will detect the presence of coliform bacteria and nitrate, two contaminants commonly found in drinking water.

High concentrations of nitrate in drinking water can cause a life-threatening condition in infants called methemoglobinemia. This illness is called "blue baby syndrome" because it causes a blue tint in the infant's skin due to lower oxygen levels in the blood. Although nitrate in drinking water is not normally considered harmful to older children or healthy adults, its presence in that water does indicate an increased likelihood that other disease causing contaminants may also be present.

Testing Your Water
Likewise, testing for coliform bacteria is important because coliform is an excellent "indicator species" whose presence indicates a strong likelihood that the water supply has been contaminated. Testing for the presence of an “indicator” species or organism that is easy to find is a good idea, since testing for every type of harmful bacteria would be difficult and very expensive. If your water sample shows the presence of coliform bacteria, then your water supply likely has some degree of contamination.

Testing for coliform bacteria and nitrate is a good idea, especially after:
  • A heavy spring or summer rainstorm.
  • Your well is flooded or damaged.
  • Your water exhibits a change in color, taste or smell.
Things to Remember
A few important things to remember about your drinking water supply:
  • Common sources of bacterial contamination are livestock waste, failing septic systems, and/or contaminated surface water that has somehow migrated into a well or aquifer.
  • Common sources of nitrate in groundwater are fertilizers, septic systems, livestock waste, and naturally occurring nitrate in the surrounding soil.
  • A water-testing lab will describe nitrate concentrations in one of two ways. The lab may describe the nitrate concentration as the amount of actual "nitrate" or as the amount of "nitrate-nitrogen." The maximum contaminant level for nitrate in a public water supply is 44 parts per million (ppm), which is the equivalent of a nitrate-nitrogen concentration of 10 ppm.
  • If unacceptable nitrate levels are found in your water, do not boil the water in an attempt to purify it. Boiling the water will not reduce the nitrate levels, but will actually increase the concentration of nitrate contamination in your drinking water due to evaporation. Instead of boiling your water, use bottled water until you can treat the well water, eliminate the pollution source, or make any necessary repairs.
While the Minnesota Department of Health cannot require someone with a contaminated private water supply to correct the condition, it certainly does recommend that you find and fix the problem, disinfect your water system, and then submit another sample for analysis. Your local department of public health, a licensed well driller, or a pump repairman can further explain the proper techniques for disinfecting a well.

More Information
Contact the Scott County Environmental Health Department at 952-496-8475 for further information.