Does bleach kill coliform bacteria?

Bleach is the suggested method for killing coliform bacteria, which seeps into wells from soil and surface water, according to PennState Extension. Testing water and follow-up prevention is recommended to keep coliform from returning.

Chlorine bleach is used to shock the water system and kill coliform bacteria. Not all coliform bacteria is harmful, however bacteria can cause illness if levels in water are high, per PennState Extension. E. coli and fecal bacteria are commonly tested as they pose higher threat of illness.

If coliform is present in water, it could be a one-time contamination or a leak in the well system. It is found in shallow wells and springs where the water cannot be naturally filtrated, according to PennState Extension. Testing water, to gauge the bacteria level, determines if shocking the system with bleach is necessary.

One-time shocking doesn't remove recontamination chances, indicates Professional Home Inspection Service. Checking piping and seals, adding a sanitary cap, and grading to correct standing water decrease recontamination chances. Chlorination treatment systems and UV light systems can be installed if the contamination is corrected.