Coliform is a type of harmless bacteria found naturally in the environment and in our bodies. According to the EPA, coliform is “not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present.” The presence of coliform in water is a strong indicator of recent sewage or animal waste contamination, which may contain disease-causing organisms like E. coli.
Short for Escherichia coli, E. coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. Unlike other coliform bacteria, E. coli can cause severe health problems, including bloody diarrhea, vomiting, stomach cramps, and fever. These symptoms can last from 2 to 10 days, and in some cases can be fatal, according to the Oregon Health Authority.
E. coli from human and animal wastes may be washed into creeks, rivers, streams, lakes, or ground water by rainfall, snow melts, or other types of precipitation. E. coli infection commonly occurs when these waters are used as sources of drinking water without proper treatment.
Interestingly, the EPA’s maximum contaminant level for coliform bacteria is measured not in parts per million, but in the amount of coliform-positive water samples taken in one month. For users who test 40 or more times a month (this primarily applies to municipal treatment centers where water testing is performed routinely), 5% of samples may test coliform-positive in one month to meet EPA standards. For users who do not test as frequently, i.e. most homeowners, EPA standards dictate that no more than one sample a month may be positive.
We carry multiple test kits with bacteria tests, including our WaterSafe Well Test Kit and Well Test Pro Kits I and II. We also sell individual bacteria tests like the EZ Cult 24 hour test, which can be used at home, but requires the use of a UV light for result analysis. It’s a good to have your results confirmed in a lab if possible, but note that the bacteria in your sample may dissipate out of the water while the sample is in transit. For best results, find the lab closest to you and pre-plan a way to get your sample there quickly before testing.
If you draw water from a private well and your well tests positive for E. coli, we recommend taking the following safety measures:
If bacterial contamination becomes a recurring problem, try to identify the source of the problem (such as a defective well seal or cracked casing) and fix it. You can also investigate the feasibility of drilling a new well, or install a disinfection unit utilizing either chlorination, ultraviolet light, or ozone to kill bacteria and viruses.
Distillers can also provide a reliable way to disinfect water at a point-of-use, i.e. at your faucet. Ceramic point-of-use filter systems such as the Doulton Twin HIP/IDIY will filter E. coli bacteria very effectively.