How much bleach does it take to shock a well?
About 3 pints of plain 5.25% bleach per 100 gallons of well water lands near the 200 ppm target extension services publish. A typical 6-inch well with 100 feet of standing water holds about 150 gallons, so figure roughly 4 to 5 pints for that well, plus more for the pressure tank and plumbing.
The math: one gallon of 5.25% bleach in 100 gallons of water gives about 525 ppm of chlorine, so 3 pints (0.375 gallons) gives roughly 200 ppm. Your well's gallons come from three numbers on its record: total depth, static water level, and casing diameter, at 0.0408 times diameter squared gallons per foot of standing water.
Use plain, unscented, fresh bleach only; splashless and scented versions carry additives that do not belong in a drinking water well, and old bleach loses strength on the shelf.
The honest caveat: dosing is the easy half. Bleach loses most of its power above pH 7.5, burns itself up on iron, and struggles with biofilm, which is why our kit doses chlorine dioxide instead, sized to your exact well.
Want the dose sized to your exact well?
We pull your well's dimensions from your state's official record and pack a chlorine dioxide kit to them, from $399.
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