E. coli

Not all E. coli strains cause illness, but their presence can indicate other harmful pathogens in water, because E. coli is a direct result of fecal contamination. Symptoms of ingesting harmful E. coli include abdominal cramps and diarrhea. Some cases of E. coli exposure can lead to hemorrhagic colitis, an acute illness that results in cramps, watery diarrhea, and lower intestinal bleeding with occasional vomiting and fever. Certain strains of E. coli may cause hemolytic uremic syndrome or renal failure. These health effects are primarily a danger to young children, the elderly, and people with compromised immune systems.

• E. coli bacteria live naturally in the gut and feces of most warm-blooded animals, including humans
• When E. coli is found in water, it is a direct result of fecal contamination
• While almost all surface water contains some E. coli bacteria, groundwater tends to be free of bacteria unless it has been contaminated by surface runoff
• The presence of E. coli in tap water can indicate inadequate water treatment or a problem with the local water distribution system
• Agriculture and livestock waste, as well as poorly maintained septic tanks or sewage disposal systems, can lead to E. coli contamination in source water

Water filters certified under the following NSF standards are effective at removing E. coli: