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 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.
For more information regarding treatment options see UV Bacteria Systems.