Coliform Bacteria

Sources of Coliform Bacteria


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Sources of Coliform Bacteria

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Safety Guidelines

Testing for Coliform Bacteria

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Sources of Coliform Bacteria

There are several ways in which Coliform bacteria and other pathogens can enter into your water supply system.

Coliforms from animal feces may enter water supplies directly or migrate through the soil and contaminate groundwater, especially during heavy rains or spring flooding.

Contamination may happen when maintenance has been performed on the water supply system. Other potential sources of contamination are: effluent from septic systems or sewerage discharges, faulty in-ground sewage disposal or agricultural run-off.

Poor well site selection, maintenance and construction (shallow dug wells) can also increase the risk of bacteria and other harmful organisms to get into a well water supply.

well water runoffThe water can be easily contaminated if the well is located in the depression when run-off is collected.

Contamination can also occur during floods, when flood water overtops the well casing.

Shallow wells, less than 60 feet deep, are more prone to contamination than deeper ones, as shallow ground water may not be sufficiently filtered by the soil and porous material above the water table to remove surface bacteria. Shallow groundwater can be also influenced by the on-site disposal of the waste-water.

If a septic system is too close to the well, or not working properly, this may also be a source of contamination.

Open WellOpen wells, allowing animals such as rodents to fall into, or having even small openings letting the insects getting in and out are predisposed to Coliform contamination.  Backflow from outside hoses, caused by negative pressure in the plumbing, can bring dirty water back to the well, and contaminated clean water with bacteria. Faulty check valves also contribute to the problem.

Unsanitary plumbing can cause contamination, even when a well is properly constructed and located. This is because unlike most municipal water supplies, groundwater does not contain a small amount of chlorine, that serves to prevent the growth of bacteria within the plumbing.
Forgetting to regularly service water treatment filters can allow bacteria to accumulate and grow.