Parameter: These are the general water quality indicators or properties that were tested in your water. Your drinking water scan includes measurements for Primary (Health Related) and Secondary (Aesthetic or Nuisance), contaminants in drinking water. All parameters, not designated either Primary or Secondary, are considered indicators.

Results: These numbers indicate the concentration of each water quality parameter in your water sample. You should compare your results to the EPA public drinking water standards.

EPA Standards: There is no federal or state law or regulation that requires testing or that sets water quality standards for private water supplies. It is recommended however, that private water supply owners maintain their water quality to the same standards required by law for public water supplies. These acceptable limits should be used as guidelines for your own water supply when evaluating your test results.

*When results exceed the EPA’s Secondary (Aesthetic) standards for drinking water, many people may find using the water displeasing. The water may leave stains, have an odor or color, spot glasses in the dishwasher, corrode plumbing or have other displeasing characteristics.

*When results exceed the EPA’s Primary (Health Related) standards for drinking water, it is considered to be unsafe to drink until the problem is corrected.

Units of measure: The concentration unit is the amount of a given substance (weight) in a specific amount of water (volume). The most common concentration unit used is milligrams per liter (mg/L) which, in water, is approximately equal to one part per million (ppm), or one part contaminant to one million parts water. Some contaminants have units that are specific to the test like those used for radon, hardness, conductance and turbidity. Others like pH, are expressed as an index number and not in terms of concentration, and therefore have no units. Even with the most modern equipment, there are limits to which a laboratory can determine the amount of a given contaminant in water. If the amount of a substance is so small it cannot be measured, the result will be indicated as Not Detected.

  • mg/L = Milligrams per Liter (also parts per million)
  • ug/L = Micrograms per Liter (also) parts per billion)
  • SU = Standard Units
  • N.T.U. = Nephelometric Turbidity Units
  • C.U. = Color Units
  • T.O.N. = Threshold Odor Number
  • pCi/L = PicoCuries per Liter