Emergency Drinking Water Bleach Dose

Scope8 drops of 6% bleach or 6 drops of 8.25% bleach per gallon, doubled when the water is cloudy, colored, or very cold. Nobody counts 440 drops, so this calculator scales the table's per-gallon rate to any container and converts the drops to teaspoons and millilitres, then reports the dose they actually produce in mg/L. A 55 gallon drum of cloudy flood-area well water with an 8.25% bottle takes 660 drops -- 6.88 tsp, 33.9 mL, about 13.4 mg/L -- and the same drum with a 6% bottle takes 440 drops, 4.58 tsp, at the base rate. The doubling is applied after the water is settled and filtered through cloth or a coffee filter, not instead of it. The calculator also reports where the table disagrees with itself. Every row implies a drop of 1/96 teaspoon except 2 gallons of 6%, printed as "16 drops (1/4 tsp)": 16 drops is 1/6 tsp, so measuring the printed teaspoon doses 1.5 times the counted rate -- about 9.8 mg/L against 6.5, the same as Ready.gov's 1/8 tsp per gallon. The mg/L is a dose from the label strength, accurate to roughly 10%, not a measured residual; stir, stand 30 minutes, and check for a slight chlorine odor, and without one dose again and wait 15 minutes more. It does not treat water contaminated with fuel, solvents, or other chemicals, does not reliably inactivate Cryptosporidium, and does not replace boiling under a boil-water notice. Scented, splash-less, and color-safe bleach is excluded. The EPA and CDC emergency disinfection guidance, the local health department, and the utility's public notice govern.

Formula or tabledrops = table rate x gallons (8 drops per gallon of 6%, 6 drops per gallon of 8.25%, other strengths scaled from the 6% row to the same chlorine mass); doubled for cloudy, colored, or very cold water after settling and filtering; teaspoons = drops / 96 at the table's implied 1/96 tsp drop; mL = drops x drop volume; dose mg/L = mL x strength% x 10 / litres of water.

Source and editionEPA "Emergency Disinfection of Drinking Water" bleach table and procedure (stand 30 minutes, check for a slight chlorine odor, redose and stand 15 minutes more), read at epa.gov on 2026-09-30, and CDC "How to Make Water Safe in an Emergency", both by name. The local health department and the water utility's boil-water or do-not-drink notice govern.

Free accessThe EPA and CDC emergency disinfection pages are free public federal guidance; the per-gallon rates are restated and scaled, and the dose is a mass balance on the label strength.

What governsEstimate. Operator of record and primacy agency govern.

API field nameswater_volume, volume_unit, bleach_strength_pct, water_condition, drop_volume_ml, base_drops, base_tsp, base_ml, base_dose_mg_l, applied_drops, applied_tsp, applied_ml, applied_dose_mg_l, table_counted_dose_mg_l, table_measured_dose_mg_l, table_measured_ratio

• One drop is 1/96 teaspoon about 0.0513 mL, the volume every row of the EPA table implies except the 2 gallon 6% rowEPA Emergency Disinfection of Drinking Water
• Strength read as grams per 100 mL the nominal label strength, accurate to roughly 10%; an old bottle delivers less than its labelmass balance
• Double for cloudy, colored, or very cold water applied after settling and filtering, not instead of itEPA and CDC emergency disinfection guidance