Total Coliform Bacteria In Drinking Water

Total Coliform Bacteria

Preface: Of all the different types of analysis we perform on a regular basis, by far the most common is the Total Coliform Test. This test, probably more than any other single test, gives you a better overall indication about the general potability of a source water. Coincidently, it is the analysis required by the EPA for water operators to perform more often than most any other, with the exception of chlorine residuals if a chlorinated system and pH. All source water has normally occuring bacteria, or normal flora, as it is referred to. These bacteria is not generally harmful in healthy individuals. When we find Coliform bacteria, however, it paints a slightly different picture, as you can read below...

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 ha ve 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. 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 drinkin' 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.

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 e xample, 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.

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.

For more tips and helpful hints, go to http://www.Aquacheck-VT.com and check out the Water Wisdom section. You can also sign up for our free newsletter there!

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