e. coli is a dangerous bacteria that can cause gastro-intestinal illness and even death in humans.  e. coli is a bacteria that is naturally found in the guts of ruminant animals such as cattle.  Rural water systems are the most susceptible to e. coli contamination.  e. coli in the feces of cattle or other animals can be transported by water and may end up in water wells or in lakes and rivers that may act as a primary water supply for many people.

The presence of any e. coli in a water sample is cause for immediate concern.  The presence of any e. coli makes water completely unsafe to consume.  All rural health units and departments of health will test a water sample for e. coli bacteria usually for free.  If e. coli is detected there are several ways that a homeowner can make the water drinkable.  The easiest and safest way is to use an NSF certified UV system.  UV light is capable of rendering e. coli bacteria completey harmless.