Coliform

What is coliform? Coliform is a rod-shaped bacteria which are always present in the digestive tract of warm-blooded animals, including humans.  Coliforms are found in human and animal waste, and are also found in water, plants and soil.

Most coliform bacteria don’t cause disease, but some such as a few strains of E. Coli can cause illness.  Positive coliform bacteria tests of food and water indicate the possibility of fecal pollution, and are often associated with the outbreak of disease.

Ground water pollution caused by fecal contamination is a serious problem, and can be associated with disease.  But, testing for every possible type of bacterial infection would be far too expensive to undertake.  Coliform bacteria have the same origin as disease-causing bacteria, ie. fecal contamination.  Since it would be cost-prohibitive to test water for every type of possible bacterial infection, laboratories test for indicator organisms such as colliform bacteria.

Total coliform count offers a general indication of the condition of water supply.  The higher the count, the poorer the water’s condition; however total coliforms can come from sources other than feces, which means total coliform count can only give a general indication of water supply condition.  This does mean though that a positive total coliform count should still be considered an indication of fecal contamination.

Fecal coliforms are the coliform that is found in the digestive tract of animals and humans, and is an indicator of fecal contamination.  A high count of fecal coliforms is considered an accurate indicator of animal or human waste.

Escherichia coli (E. coli) is a major species of the fecal coliforms.  Of the groups of coliforms present in total coliforms, E. coli is not found growing naturally in the environment and is therefore the best indicator of the presence of pathological bacteria in your drinking water.  E. coli can cause serious illness.

If coliforms are found in your drinking water, it is an indication of possible contamination and your risk of contracting an illness from your drinking water is increased.  This means that you should repair or modify your drinking supply as soon as possible.  Until your water source is repaired or modified, water should be boiled before consuming it until retesting indicates the contamination has been removed.

If you use a water well system for your drinking supply, the most common ways contamination can get into your water include:

  • Missing or defective well caps
  • Cracks or holes in the well casing
  • Seepage along the outside of the well casing
  • Flooding in wells that are in low-lying areas

What you need to do in order to restore clean drinking water is repair the problem, “shock” the well, and then test again before allowing anyone to drink water that has positive bacterial coliform counts.

 

References
Health New York Government: Coliform Bacteria in Drinking Water Supplies
http://www.health.ny.gov/environmental/water/drinking/coliform_bacteria.htm
Wikipedia: Coliform Bacteria
http://en.wikipedia.org/wiki/Coliform_bacteria