BACTERIA IN WATER

Bacteria in Water

Bacteria in Water

Introduction

The presence of bacteria and pathogenic (disease-causing) organisms is a concern when considering the safety of drinking water. Pathogenic organisms can cause intestinal infections, dysentery, hepatitis, typhoid fever, cholera, and other illnesses. Human and animal wastes are a primary source of bacteria in water. These sources of bacterial contamination include runoff from feedlots, pastures, dog runs, and other land areas where animal wastes are deposited. Additional sources include seepage or discharge from septic tanks, sewage treatment facilities, and natural soil/plant bacteria. Bacteria from these sources can enter wells that are either open at the land surface, or do not have water-tight casings or caps.Insects, rodents or animals entering the well are other sources of contamination. Old wells were dug by hand and lined (cased) with rocks or bricks. These wells usually have large openings and casings that often are not well-sealed. This makes it easy for insects, rodents, or animals to enter the well.

Another way bacteria can enter a water supply is through inundation or infiltration by flood waters or by surface runoff. Flood waters commonly contain high levels of bacteria. Small depressions filled with flood water provide an excellent breeding ground for bacteria. Whenever a well is inundated by flood waters or surface runoff, bacterial contamination is likely. Shallow wells and wells that do not have water-tight casings can be contaminated by bacteria infiltrating with the water through the soil near the well, especially in coarse-textured soils. (Roper, 2004, 427 - 434)

Older water systems, especially, dug wells, spring-fed systems and cistern-type systems are most vulnerable to bacterial contamination. Any system with casings or caps that are not water-tight are vulnerable. This is particularly true if the well is located so surface runoff might be able to enter the well. During the last five to 10 years, well and water distribution system construction has improved to the point where bacterial contamination is rare in newer wells.

Discussion

Bacterial contamination cannot be detected by sight, smell or taste. The only way to know if a water supply contains bacteria is to have it tested. The Environmental Protection Agency (EPA) requires that all public water suppliers regularly test for coliform bacteria and deliver water that meets the EPA standards. There is no requirement to have private water wells, springs or other sources tested, it is up to the individual homeowner. For Public water supplies, frequency of testing depends on the size of the population served. Bacteria test results are available from the supplier and there must be a public notification if the water supply does not meet the standard. For Homeowners, I would suggest that your source be tested at least four times per year (quarterly) and then at least annually.

Owners of private water supplies are responsible for having their water supply tested to ensure it is safe from bacterial contamination. Generally, private water supplies should be tested for bacterial safety as follows:

at least once a year;

when a new well is constructed;

when an existing well is returned to ...