What Causes Presence of Coliform in Water?

What is Coliform?

Coliforms are bacteria that are always present in the digestive tracts of animals, including humans, and are found in their wastes. They are also found in plant and soil material.

Are Coliform Bacteria Harmful?

Most coliform bacteria do not cause disease. However, some rare strains of E. coli, particularly the strain 0157:H7, can cause serious illness. Recent outbreaks of disease caused by E. coli 0157:H7 have generated much public concern about this organism. E. coli 0157:H7 has been found in cattle, chickens, pigs, and sheep. Most of the reported human cases have been due to eating under cooked hamburger. Cases of E. coli 0157:H7 caused by contaminated drinking water supplies are rare.

Coliform Testing

Testing for bacteria is the only reliable way to know if your water is safe. You cannot tell by the look, taste, or smell of the water if disease-causing organisms are in it. The Illinois Department of Public Health recommends that well owners test their water for coliform bacteria at least once a year. If you have experienced bacteria problems in the past, it is recommended that you test your well more frequently.


Bacterium can be eliminated with the following processes:


Chlorine, Ultraviolet Light, or heavy dosing of hydrogen peroxide.


The Illinois Department of Public Health recognizes only Chlorine as an effective method of eliminating this bacterium and mentions that either chlorinating the well or continuous chlorination is the proper method for eliminating this issue. Chlorinating the well is only a temporary fix to the issue.


CONSIDERATION: Treatment is tricky and many factors must be considered when filtering this contaminant. Flow rates of the well, type of well system and size of plumbing. These bacterium create a “slime” in your water which coats the water molecule and makes treatment very difficult. Bacterium feeds on oxygen and or the organics in your water. Removing the organic without the assistance of chlorine is exceptionally difficult because the bacterium coats the filter material, making it ineffective.


Chlorine injection of potable water is the most successful method of treatment for these bacteria. However, chlorine injection may be cost prohibitive and the system requires regular maintenance.

Schedule In-Home Water Test

Use the button below to choose a time. Our team will be in touch to confirm the day, time and location of your appointment.