Coliform bacteria are microorganisms commonly found in surface water, soil, decaying vegetation, and the intestinal tract of humans and animals. While most bacteria are harmless to human health, some are capable of causing disease. Coliform bacteria in a water sample indicate a potential pathway for fecal wastes and other pathogenic organisms to enter your well. Possible health threats include gastrointestinal diseases, hepatitis, and others. The water test used in laboratories to detect coliform bacteria also detects E. coli which is a type of coliform bacteria. If E. coli is present, the water is likely to contain disease-causing organisms from fecal contamination. These bacteria die off fairly quickly outside the host, usually within 30 days. When a well shows a persistent presence of coliform bacteria, it is a strong indication that bacteria are continuously entering the well as the water is withdrawn. The following test are run for bacteria and coliform analysis: • Coliform (total and e. coli) Drinking Water - positive/negative • Coliform (total and e. coli) Drinking Water - quantified • Fecal Coliforms for Surface/Wastewater - quantified • E. coli for Surface/Wastewater - quantified • Swimming Pool Water Coliform - quantified (upon request)

• Once a year for monitoring the health of the well. • When a new well is constructed, or any component of the well system has undergone replacement or repair, including pump, pressure tank, piping, or any other component. • When flood waters or surface water inundates well. • When you suspect bacterial contamination by continuous illness in the house.

If your drinking water source is from a private well, testing on a yearly basis is ideal to monitor the health of your well. Bacterial contamination does not change the appearance, smell, or taste of water. Testing by a certified lab is the only was to determine if the water is free of harmful contaminates. Results of Coliform Analysis “Negative” - Coliform bacteria are absent in the water sample. Water is considered bacteriologically SAFE. “Positive” - Coliform bacteria are present. Water supply is considered bacteriologically UNSAFE. Re-sampling is advised. If your water sample is Positive for both Total Coliform and E. coli, do NOT drink, cook, or brush teeth with the water. Contact your local health department. Further water testing should be done after corrective measures have been take.

Each of the instances below identifies a situation that may produce a false positive result. In many cases, sampling errors creating positive bacterial results can be distinguished from those in which bacteria are attributed to poor construction and/or poor soil filtration. When taking additional bacterial samples sampling errors are not likely to be repeated whereas real construction or filtration problems will show either a constant or highly irregular presence of bacteria. Neither one good nor one bad bacteria sample can be considered sufficient testing to judge the long term consistency of a system’s water quality. 1. Sample Collection was Improperly Performed Improper bacteria sample collection is a common error. Improper sampling can make a good water sample appear to be bad. Click here for more information. 2. Poor Well Construction Poor well construction is the most prevalent cause of bacterial contamination. There are numerous problems that can occur with a dug well including: o A lack of mounded backfill around the outside of the well casing. o Insufficient casing height above the ground level. o Inadequate or leaky well cover or cap. o Holes, cracks, or unsealed joints in the sidewall of the upper portion. 3. New Construction, Replacement, or Repair When a submersible pump is taken out of a well or when a new pump is prepared for installation, it is typically placed directly on the ground near the well. When this happens, bacteria-lade dirt often adheres to the pump, the water discharge line, and/or the electrical power cable. This material then contaminates the well when the pump is installed. The installation of any new well normally allows for substantial bacteria to enter the fractures of the bedrock or the soil around the outside of the dug well casing. Mud and soil particles protect these bacteria from disinfection. Sustained flushing is necessary to remove this dirt, mud, pulverized rock and bacteria. Disinfection should be conducted only after first flushing the loosened material. 4. Physical Damage to the Aquifer’s Filtration Capability Bacteria are normally removed from groundwater as the water percolates through soil. It is possible, but unlikely, that bacteria will move through the soil or bedrock fractures for a significant distance. Drilling a new well can also create localized short-term bacterial contamination of bedrock fractures. Normally these construction activities will be short in duration. Conditions which normally remove filtering soil and expose fractures in the bedrock include: o Road cuts through bedrock outcrops. o Excavations into bedrock for swimming pools or house foundation. o Artesian well drilling on other lots. o Abandoned but uncapped bedrock well on other lots. Water quality should improve once the soil is replaced and has achieved compaction. There could be weeks of time between the replacement of soils and the end of the bacterial presence. 5. Biological Activity Occurring within Treatment Equipment and Piping Water treatment equipment often uses sand or other media to filter bacteria from drinking water. This action typically brings bacteria together on the filter media. In such cases, the filtration provides an easily- obtained, concentrated food supply for these bacteria to sustain themselves creating a “biofilm”. The “biofilm” created on the inside of pipes and tanks can cause a coliform detection.