First, let me address pathogens (disease causing microbes). Our water source is deep well groundwater. Most of these types of sources have the advantage of being pathogen-free and ours is no exception. During the extended period of time it takes to reach our well intakes, any pathogen in the recharging water from the surface will die from lack of host presence and predator organism activity. Filtration by the natural properties of the surrounding ground formations also tends to eliminate pathogens-especially the larger ones. We guard against pathogens entering our distribution system by keeping a satisfactory system pressure as continuously as possible. The residual chorine we maintain in the water kills almost all pathogens that might enter the system.
Bacteria of the coliform group almost always accompany pathogenic microbes. Since coliforms are easily detected, testing for them has become a matter of routine in all public water systems. We submit samples at least twice a month and, over a year's time, from seven different points in our distribution system. We also submit raw water samples on a quarterly basis. In the last twenty-four years we have had only two bad samples (and both were unconfirmed by required repeat sampling) and one questionable sample. All three were likely to have been from sampling error. The test is so sensitive that touching the rim of the sample bottle or the inside surface of the cap with a finger will cause a bad sample. The test can detect as few as one active bacterium per one hundred milliliters of water sample. We submit our samples to the Indiana State Board of Health Laboratory in Indianapolis or, because of time or shipping constraints, to a certified local laboratory in Lafayette.
Giardia lamblia and cryptosporidium parvum are one-celled animals (protozoa) that cause gastrointestinal disturbances. Watery diarrhea, stomach upset and cramps, and a slight fever are some of the symptoms of infection. Our water source is intrinsically safe from these pathogens. Water travels too long a time from any possible sight of contamination to the intake of our deep wells for them to survive. Surrounding clays and fine sands also tend to further slow them down or filter them out since they are larger microbes (in the order of eight to nineteen microns). We construct and maintain our distribution system to exclude possibilities of contamination from these protozoa. I know of no instance where these organisms caused disease via our water system.
There are many other kinds of microbes that are not pathogenic, and are present in the best water systems. Iron and sulfur bacteria are one noteworthy group. These common bacteria can cause unpleasant odors and obnoxious brown slimes in some places where a chlorine residual is absent. They are not indications of pathogenic contamination. Their nutrient supply is often inorganic. Back to Contents
Edited 07/02/2004