E. coli / Total Coliform Bacteria
Pathogen · measured in MPN/100mL
Indicator bacteria used to signal fecal contamination and the likely presence of disease-causing pathogens in water.
Common sources
Human or animal fecal contamination — failing septic systems, agricultural runoff, wildlife, and stormwater overflow into wells, streams, or recreational water.
Health risks
Indicates a meaningful risk of waterborne gastrointestinal illness (diarrhea, cramps, vomiting) from pathogens that often accompany coliform bacteria. Certain E. coli strains (e.g. O157:H7) can cause severe illness including hemolytic uremic syndrome, particularly dangerous for young children, the elderly, and immunocompromised people. The EPA drinking water standard is zero detectable total coliform.
Sources & further reading
- CDC — E. coli (Escherichia coli)
- WHO — Guidelines for Drinking-water Quality, 4th edition
- EPA — Total Coliform Rule
How ClearDive rates severity
Readings are bucketed for map color-coding using thresholds referenced from EPA regulatory limits where available. This is a simplified public-awareness scale, not a substitute for certified lab analysis.
How to test for it
Field presence/absence test kits (e.g. Colilert-style) give a same-day yes/no result; quantitative MPN or membrane filtration testing at a certified lab is needed for an exact count.