Private Water Well Owner Tip Sheet

Hydrogeology, Geology, & Environmental Issues / Field Methods & Procedures

Date posted: 01/21/16

The NGWA folks offer the private water well owner tip sheet. Disinfection and a well inspection are recommended when a well water tests positive for microorganisms such as bacteria, viruses, and protozoa (single-cell animals). Wells are routinely tested for coliform bacteria or other organisms in soil or vegetation, and in the intestinal tract of warm-blooded animals. Most coliforms are harmless. Their presence indicates whether the well environment can support disease-causing bacteria. Some strains of E. coli are disease causing, even lethal. If a well tests positive for coliform bacteria, testing for E. coli may be prudent. A water well should be disinfected: 1. When the water tests positive for coliform bacteria 2. Just after well construction 3. just after well servicing If there is a well-system defect that could allow bacteria into the well. The NGWA recommends qualified water-well professionals conduct system disinfections. Proper well disinfection involves chemistry and proper application techniques, because the potential is great for well owners to improperly disinfect their well systems. Chlorine compounds are most commonly used to disinfect water wells. These compounds can be a breathing or explosion hazard. Also, NGWA recommends household bleach not be used to chlorinate wells for reasons including it is not made for use in drinking water. Recurring bacteria could indicate ... 1. A breach in the well systems sanitary seals 2. A nearby contamination source such as a failing septic system or an animal feedlot 3. The need for a well cleaning. If bacteria is recurring in your water, consult with a qualified water-well system contractor on how to proceed.