Coliform bacteria are common in the environment and are generally not harmful. However, the presence of these bacteria in water is usually a result of a problem with the treatment system or the pipes which distribute water, and indicates that the water may be contaminated with germs that can cause disease.
Fecal Coliform and Escherichia coli (commonly referred to as E. coli) are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms.
Common scenarios which create bacterial issues are; hand dug wells, buried wells, well heads very close to the surface, and/or non water tight well caps. If any of the above scenarios exist, a well professional should be contacted to correct them.