Coliform tests are used to indicate potential contamination by other bacteria and viruses. If the test sample shows that coliforms are present, you will need to shock chlorinate the well. You will then need to resample after flushing residual chlorine from your water system. Please call Environmental Health or your well pump installer for information on other testing and treatment options. In addition to sampling for coliform bacteria, Environmental Health recommends sampling for nitrates, iron, manganese, hardness, hydrogen sulfide, and sodium.
Higher levels can negatively affect pregnant women, infants, and nursing mothers.
Nitrate may also be an indirect indicator of the presence of pesticides and other organic contaminants. The alluvial aquifers near rivers are of most concern. The Oregon Health Division requires that a copy of the coliform and nitrate results be sent to them on any house sold in Oregon. Iron, manganese, hardness, hydrogen sulfide and sodium do not usually make people sick. Iron stains fixtures red, manganese stains black.