Bacteria in Water

Bacteria in Household Water

A common hazard of household water is bacteria and other micro-organisms contamination.

Short term gastrointestinal disorders and illnesses such as gastro-enteritis, giardiasis, typhoid, dysentery, cholera, and hepatitis have been linked to water contaminated by micro-organisms. They can find their way into a water supply from a variety of sources including sewage, animal wastes, or dead and decaying animals.

These generally are not a concern for those who are on a public water system. These illnesses are eliminated by the introduction of chlorine into the water supply to kill the micro-organisms that cause these problems.

The Environmental Protection Agency (EPA) requires that all public water suppliers regularly test for coliform and deliver water that meets the EPA standards.The frequency of testing depends on the size of the population being served. The test results are available from the supplier and there must be a public notification if the water supply does not meet the standard.

However, the safety of a privately-owned, individual water supply, such as a backyard well, rests in the hands of its owner.

Owners of private water supplies are responsible for having their water supply tested to ensure it is safe from bacterial contamination.


When should a test be done?

Generally, private water supplies should be analyzed for total coliform:

* at least once a year

* there is an infant in the home

* when a new well is constructed

* when an existing well is returned to service

* any time a component of the water system is opened for repair -- this includes the well, pump, pressure tank, piping, and any other components the water will contact

* whenever the well is inundated by flood waters or surface runoff

* any person or animal becomes sick from a suspected waterborne disease

* when a laboratory test indicates high nitrate and human or livestock waste is suspected.


My test came back positive. What do I do now?

Don't panic!

You may have been drinking this water for some time and had no ill effects. You and your family may have developed some immunity to the harmful bacteria present in the water but there is no assurance that you won't suffer ill effects in the future. And guests in your home who do not have this immunity may experience more immediate problems.

Septic systems are a major source of contamination of an underground water supply (well or spring), according to the EPA. Poor design, construction, and maintenance of septic systems can lead to contamination of your household water. It is recommended that your septic tank be pumped out every three to five years to reduce the probability of contamination.


How can my water be continuously disinfected?

Options include either continuous chlorination, ultraviolet radiation, distillation, and ozone treatment. There is no ideal disinfection method. Each has advantages and limitations.




Bacterial contamination of drinking water can be a problem. A water test is the only way to evaluate any micro-organisms present in a water supply. Proper well location and construction are necessary to avoiding contamination of your drinking water. If your private water supply is contaminated attempt to identify and eliminate the source of the contamination. Your water supply can be disinfected, but it is recommend that you contact a professional consultant in your area.





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