What Are the Causes of Coliform Bacteria?

Coliform bacteria live in the intestines of warm-blooded animals, including humans, and can be found in the soil, vegetation and surface waters. Coliforms themselves are not necessarily harmful though they are considered indicators. Their presence in water typically suggests fecal contamination, which can contain pathogens, including harmful strains of E. coli, cholera and hepatitis. Water most at risk for Coliform contamination is that in public lakes and home septic systems, although public water systems have been known to be affected.

Animals

• Animal feces play a large role in contamination of both public and private waters. Domesticated animals, particularly dogs, whose waste is not removed can contribute to the adulteration of home septic systems and wells. Pigeons, seagulls and other waterfowl are major causes of lake Coliform. Most beaches prohibit feeding them to discourage their presence. The Illinois State Department of Health has gone so far as to employ professional Border Collies at Chicago-area beaches to harass the gulls, which has led to a decrease in contamination. State health departments mandate regular testing of lake water during beach season, particularly after heavy rains. If unhealthy levels are present, they close the beaches until normal levels return.

Septic Systems and Wells

• Despite the fact that Coliforms live in surface soil and water, they do not affect wells and septic systems installed at a proper depth. However, a shallow or damaged well is easily contaminated. Age or impact by farm machinery or snow plows can lead to cracks, as can maintenance itself. If not properly operated, drilling equipment can cause damage, and even introduce into the system. Proper backflow devices, water-tight casing seals and a proper depth are also crucial to ensure that no surface water or storm runoff enters the system and introduces Coliforms. A safe drinking supply is critical to health. Because contamination cannot be detected by taste, smell or sight, test the water in septic systems annually.

Heavy Rains

• Heavy rains often causes flooding, during which rainwater picks up various lawn and garden fertilizers, animal wastes and other pollutants. This adulterated water may invade damaged septic systems or find its way into lakes used by swimmers. Heavy rains also overwhelm storm sewers and cause sewage overflow. This may discharge into area lakes and waterways, concentrating the naturally occurring coliform and leading to unsafe levels. Homeowners with city water can face contamination if sewage backs up in home basements.

Agricultural Runoff

• Industrial agricultural, or Concentrated Animal Feeding Operations, generate millions of gallons of liquid waste, which is housed in open-air lagoons. Prone to leaks and spills, this runoff can contaminate water supplies. Heavy rains can also contribute to leaks, which can taint water supplies, including irrigation water, which then pollute crops leading to potential E. coli contamination of food.

Bather Defecation

• Bather defecation, which results in fecal coliform in the water, can be a source of lake contamination. Children who are not toilet-trained should wear rubber pants over their diapers. Encourage all children to use the restroom prior to entering the water.