What is shock chlorination?
Last updated Reviewed by Sean Mihelich, founder of Save My Well
Shock chlorination is disinfecting a well by raising its chlorine level far above drinking-water levels, typically to 50 to 200 ppm, holding it for 12 to 24 hours, then flushing it out. It is the traditional method extension services publish for wells that fail a bacteria test. The same job can now be done with chlorine dioxide at a far lower dose.
Treating a well with a disinfectant is also called shock chlorination.
The procedure treats the whole water system, not just the hole in the ground: the standing water column, the casing walls above the water line, the pressure tank, and the household plumbing all see the dose, and a bacteria retest one to two weeks later proves the result.
The chlorine dioxide variant follows the same steps at 20 ppm, holds its strength at real well-water pH, and strips the biofilm chlorine glances off, which is the version our kit ships.
Sources
Penn State Extension, Shock Chlorination of Wells and Springs, 2025
Ohio State University Extension, Shock Chlorination of Wells (AEX-318), 2019
Minnesota Department of Health, Well Disinfection, 2024
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