{"id":2517,"date":"2014-05-07T14:41:55","date_gmt":"2014-05-07T21:41:55","guid":{"rendered":"http:\/\/support.cleanwaterstore.com\/blog\/?p=2517"},"modified":"2026-10-02T11:17:15","modified_gmt":"2026-10-02T18:17:15","slug":"sources-of-coliform-bacteria-contamination-in-home-well-water","status":"publish","type":"post","link":"https:\/\/www.cleanwaterstore.com\/blog\/sources-of-coliform-bacteria-contamination-in-home-well-water\/","title":{"rendered":"Sources of Coliform Bacteria Contamination in Home Well Water"},"content":{"rendered":"

Coliform bacteria are common in the environment, present in the soil and intestines of animals, and are generally not harmful. However, they are one of the most common water contamination problems in home well water, and their presence signals that disease-causing organisms may have found a way into your supply.<\/p>\n

The presence of these bacteria in well water or spring water usually indicates that the water may be contaminated with germs that can cause disease. These germs can even contaminate well water without any change in taste or odor to the water. Therefore, the US EPA recommends annual testing of residential water wells for coliform bacteria.<\/p>\n

\"Coliform<\/p>\n

Generally, the two categories of coliform bacteria found in well water are total coliform and fecal coliform, including E. coli. Detecting total coliform in a water source doesn’t necessarily mean the water is contaminated, but it can indicate that more harmful bacteria, like fecal coliforms or E. coli, may be present. If you detect fecal coliforms or E. coli in your well water, start by disinfecting your system and locating the source of the contamination.<\/p>\n

What’s the Difference Between Total and Fecal Coliform?<\/h2>\n

Total coliforms are common bacteria found in soil, plants, and water that signal possible contamination. Fecal coliforms, such as E. coli, come from human or animal waste and indicate a higher health risk. If tests show total coliforms only, inspect your well, disinfect, and retest. If fecal coliforms are present, treat the water as unsafe until it’s been disinfected and follow-up tests come back clean.<\/p>\n

Sources of Coliform Bacteria Contamination<\/h2>\n

When tests detect only total coliform (without fecal coliform or E. coli), the contamination most likely entered the system from the environment, often during construction, plumbing, or water main repairs. Because there are so many different ways to introduce bacteria into the system, the original well construction can often be the cause of an ongoing bacterial problem that can last for many years.<\/p>\n

\"Dairy<\/p>\n

If fecal coliform or E. coli are detected along with total coliform in drinking water, they are most likely coming from sewage that has entered the drinking water. Waste from humans, rodents, or farm animals can be a principal source of bacteria in the water. Runoff from agricultural fields, animal feedlots, sewers, or septic systems often causes contamination. Additionally, the overuse or improper storage and disposal of chemicals can poison and contaminate drinking water if they are in close proximity to your well.<\/p>\n

Why Private Wells Are More Vulnerable<\/h2>\n

Private water systems, including wells and springs, are more susceptible to coliform contamination than municipal supplies due to their proximity to potential sources of contamination. Shallow wells, in particular, are more vulnerable to contamination from surface water and soil. Weather conditions, such as heavy rain, can also increase the risk, since runoff has more opportunity to reach the well. Proper maintenance and testing are essential to catching this early.<\/p>\n

Testing For Coliform Bacteria<\/h2>\n

We recommend this state-certified lab water check test<\/a> for proper testing of fecal coliforms and E. coli. This should be strongly considered when purchasing a new home or after constructing a new well.<\/p>\n

\"Coliform<\/a><\/p>\n

Testing typically involves collecting a water sample and sending it to a lab for analysis. If the initial result is positive, a repeat sample is usually collected to confirm the presence of coliform bacteria and, if needed, determine the source of contamination. Boiling or disinfecting the water can kill coliform bacteria in the short term, but it’s essential to address the underlying source to prevent it from happening again.<\/p>\n

What to Do If Your Water Tests Positive for Fecal Coliform<\/h2>\n

If your water tests positive for E. coli or fecal coliform, start with an emergency chlorination that lasts two to five days. While you disinfect the system, vigorously boil your drinking and cooking water for one minute before using it.<\/p>\n

It’s also very important to continue testing the water because if anything happens to the chlorine residual, or if the chlorine demand changes and the consumer doesn’t know about it, the water can become unsafe again.<\/p>\n

Prevention of Bacterial Contamination<\/h2>\n

Construct your well at least a foot above ground level or build a mound of dirt around it to prevent rainwater or chemical runoff from pooling nearby and seeping into the system. If you are constructing a new well, minimize the proximity of possible sources of contamination, the further away, the better:<\/p>\n