Escherichia Coli is a coliform bacteria commonly found in the intestines of warm-blooded animals. Certain strains of E. Coli cause sickness in humans. E. Coli in water can also be a good indicator of fecal matter and other disease-causing bacteria in water. E. Coli counts are done for irrigation water samples. Regular drinking water E. Coli tests are included as part of total coliform testing.