NEWSplash!: Understanding and Protecting Yourself from E. Coli

Understanding and Protecting Yourself from E. Coli

“Child Infected With E. coli at Petting Zoo”; “City Residents Sickened by E. coli From Drinking Contaminated Water”. Such headlines are all too familiar. What is E. coli, where does it come from, what does it do to you, how can you tell if it’s in your drinking water and what can you do to protect yourself?

What is E. coli? E. coli, short for Escherichia coliform, is a group of hundreds of strains of bacteria that are considered to be fecal coliform. E. coli O157:H7 is one of these hundreds of strains of E. coli, and can cause severe illness. To understand the relationship between these various coliform bacteria groups, picture a circle that includes all coliform bacteria, or total coliform; inside this circle is a smaller circle that represents fecal coliform; and inside this circle a smaller circle that represents E. coli; and a dot inside of the innermost circle represents the strain E. coli O157:H7.

Where does E. coli come from? A poorly sealed well cap, an improperly grouted well, a well casing at or below ground level and leaks in underground piping can all allow total coliform to enter a water supply. While these coliform may be found in soil and may not be from a recent fecal source they indicate that the water is not sanitary and should not be consumed. Fecal coliform are considered to be coliform that have recently come from human or animal intestinal tracts. E.coli O157:H7 is spread to humans by healthy cattle where O157:H7 lives harmlessly in the animal’s intestines. A test for total coliform that shows up as zero, negative or absent means no O157:H7, no E. coli, fecal coliform or non-fecal coliform. On the other hand, the presence of total coliform simply indicates that at least one of the coliforms is present but does not identify which one(s).

What does E. coli do to you? Fecal coliform are normally found in the intestinal tract of humans and animals. While most of these strains of bacteria live there harmlessly, the strain of E. coli O157:H7 produces a powerful toxin in humans that can cause severe illness. Bloody diarrhea, non-bloody diarrhea and abdominal cramps are common symptoms of human infection. The infection usually arises within 2 to 4 days but may take up to 8 days to appear. While most individuals usually recover in 5-10 days certain individuals develop more severe life threatening complications. Children under age 5 and the elderly seem most susceptible. In simple terms the infection leads to red blood cell destruction and kidney failure. Kidney dialysis and blood transfusion in an intensive care unit are the usual treatment. Consult your physician if there is any concern you may have been exposed to E. coli O157:H7.

“If my water tested positive for total coliform does it mean that I have been exposed to E. coli O157:H7?” Not necessarily, even if fecal coliform or E. coli are found! So far, the confirmed infections resulting from water borne exposure to E. coli O157:H7 are rare and are usually associated with exposure to animal waste.

What can you do to protect yourself? Analysis for total coliform is the most frequent test performed to help determine the safety of drinking water. Water that comes from a properly protected ground water supply should have no coliform present. The presence of any coliform indicates that the water supply has a connection with some unsanitary source. This may be as simple as insects getting into the well or may be a more serious connection with human or animal waste. In either case, the water should not be consumed without proper treatment. Boiling water for one minute at a rolling boil kills coliform and other disease producing organisms. Various purifiers can also kill harmful organisms if properly installed. Protecting yourself and your well from contact with human or animal waste is always prudent. Private wells should be tested at least once a year. Every nine months is a better plan, as it results in the water being tested in various seasons. For more information, see

The best protection against E. coli in drinking water is “Know What You Drink”, and test your well water frequently and regularly.