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Total Coliform - Testing Water for Bacterial Contaminants WaterAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com What is Total Coliform? Why do we test water for coliform bacteria? When do we test for fecal coliform? Escherichia Coliform / E. coli

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Total Coliform Bacteria Information for Homeowners

The photos shown here illustrate the simple and inexpensive Total Coliform Test procedure. When the reagent is added to a properly-collected water sample, the liquid remains clear (left hand photo) if the total coliform count in the sample is less than 1 colony-forming-unit or 1cfu/100ml and turns yellow (right hand photo) if the total coliform count is above 1 cfu/100ml of water in the water test sample.

What are "Total Coliform Bacteria" and why test for them? Scott Bradley, Aquacheck Water Testing Laboratory What exactly are Total Coliform bacteria and why do we test for them in our drinking water? Total Coliform bacteria are part of a family of bacteria called, Enterobacteriaciae, or Enterics, for short. Coliform bacteria have some interesting characteristics that allow us to use them as indicator organisms. In this case, a Coliform present sample in drinking water indicates that the source is, or recently has been infiltrated by surface water. [Coliform bacteria are almost always present in surface water.] We use Coliforms to help us determine this, because Coliform bacteria are found throughout the environment, as well as on most plant material. They live longer than the pathogenic (disease-causing) microbes we don't want you to get, so it allows us to culture them in the lab. Finding Coliform bacteria in a drinking water sample does not mean anyone is going to become ill. After personally analyzing over fifty thousand individual Coliform tests, I wish I had a nickel every time someone would say to me something like, "I've been drinking' this water for over seventy years, and I never been sick from it once!" While that may be all well and true, drinking water that contains certain contaminants has been one of the leading causes of major disease outbreaks, historically speaking.

Will Coliform bacteria in water make you sick?

When we find Coliform bacteria in your drinking water sample, as stated above, it simply indicates that the source is, or recently has been compromised by surface water. We're not so concerned about the Coliform bacteria themselves, but the "red flag" if you will, is that we don't know what else may have gotten in your drinking water system via the same route that the Coliform bacteria entered. Some types of bad microbes we don't want you to ingest, for example, would be Klebsiella, Shigella, Cryptosporidium, Giardia, or Salmonella, just to name a pesky few!

Most drilled wells are free from Coliform bacteria, but many dug wells contain Coliform. This is not surprising, since dug wells are a surface water source, which means it is above the bedrock layer. Dug wells, can be an excellent source of drinking water, but extra care should be taken to be sure there is adequate separation from the well with respect to pets, farm animals, and runoff.

If you have a dug well, the volume and taste are fine, but it keeps getting Coliform bacteria, then a viable and effective option may be to install an ultraviolet disinfection system, which kills the bacteria and other microbes by separating, or denaturing the DNA or RNA of their cells. This works well because it doesn't change the chemistry of the water like some other disinfection methods, such as chlorination.

However any water treatment system requires care and monitoring, lest you think it's working when it's not. Further, the presence of surface water in your water supply might mean that other surface contaminants, such as chemicals, are also present. If this is the case, a UV-light is not going to remove them. This is why further testing of your water may be in order before deciding just what water treatment system should be installed.

Finally, if Total Coliform bacteria is found in a drinking water sample, then the sample is also checked for a type of fecal Coliform bacteria, which is always Escherichia Coliform, or E. coli. The presence of E. coli may mean a septic or leach field infiltration, or in a dug well, it just may be a squirrel or field mouse that tried to make his home in your well! We'll cover well disinfection in another session.

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Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Scott Bradley, author. Scott Bradley is Laboratory Director for Aquacheck Laboratory, Inc. PO Box 87 05151 1-800-263-9596. This article appeared in Aquacheck Laboratory's Water Wisdom Tips and Newsletter, Issue # 1, www.Aquacheck-VT.com offers other water supply tips in its Water Wisdom section. The laboratory also provides water test kits and offers a free newsletter.
• Daniel Friedman - editor
• Technical reviewers are invited to comment or ask questions - contact us

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