Certain aquifers throughout the state are more likely to contain water with excessively high concentrations of particular naturally occurring minerals and chemical compounds, mainly due to the types of minerals present in the aquifer.  These inorganic constituents include major ions such as calcium, magnesium, silica, chloride, sulfate, and nitrate; trace metals (or semi-metals) such as iron, manganese, arsenic, and fluoride; selenium, uranium and radionuclides.


Coliform is the most commonly used indicator of bacterial contamination. The presence of coliform bacteria is an “indicator” of a well’s possible contamination from human or animal wastes. Total coliform are a broad category of bacteria, most of which pose no threat to humans. Some come from fecal matter; others naturally occur in soils, vegetation, insects, etc. The presence of coliform bacteria in well water can be a harbinger of worsening water quality. In some cases, more specific tests for fecal contamination, such as E.coli, may be used.

Lead can enter drinking water when plumbing materials that contain lead corrode.  The most common sources of lead in drinking water are lead pipes, faucets, and fixtures. In homes with lead pipes that connect the home to the water main, also known as lead services lines, these pipes are typically the most significant source of lead in the water.  Lead pipes are more likely to be found in homes built before 1986.  Among homes without lead service lines, the most common problem is with brass or chrome-plated brass faucets and plumbing with lead solder.