E. coli in Drinking Water

🩨 Health Effects

E. coli is a fecal indicator organism. Its presence indicates direct fecal contamination and is a serious health concern. E. coli can cause severe gastrointestinal illness and certain strains (like O157:H7) can cause kidney failure, especially in children.

📍 Sources in Water

Enters water from human sewage, animal waste, and stormwater runoff. Detection indicates a treatment failure, damaged distribution pipes, or contaminated source water. E. coli violations require immediate public notification.

✅ What To Do

Follow any boil water advisory or "do not drink" notice immediately. Use bottled water until the advisory is lifted. E. coli violations require corrective action and are among the most serious water quality events.

📜 Regulation History

E. coli testing became required under the 1989 Total Coliform Rule and was strengthened under the 2013 Revised Total Coliform Rule (RTCR). Any detection of E. coli is an automatic MCL violation requiring immediate public notification (within 24 hours). The WHO also requires zero E. coli per 100 mL sample in treated drinking water.

🔬 How To Test Your Water

Certified lab tests for E. coli cost $15-$30 and require a sterile sample. Results are available within 24 hours. Home presence/absence test kits are available for $10-$25. Private well owners should test after flooding, heavy rains, or any changes in taste, color, or odor of their water.

💧 Which Filters Remove E. coli?

UV disinfection (NSF/ANSI 55 Class A certified, delivering at least 40 mJ/cm2) is the gold standard for home treatment of E. coli. Reverse osmosis also removes bacteria. Ceramic filters with pore sizes of 0.2 microns or smaller are effective. Boiling water for 1 minute is the simplest emergency treatment.

🔗 Related Contaminants