Water Quality

The National Ground Water Association (NGWA) recommends well owners test their water at least annually for bacteria, nitrates, and any contaminants of local concern. Total 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 is 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. Common sources of nitrate to well water are fertilizers, septic systems, animal manure, and leaking sewer lines.

Nitrate also occurs naturally from the breakdown of nitrogen compounds in soil and rocks. High levels of nitrate in well-water present a health concern and can also indicate the presence of other contaminants, such as bacteria and pesticides. Drinking large amounts of water with nitrates is particularly threatening to infants (for example, when mixed in formula).