Water Treatment Dosage Calculator
Calculate exact bleach dosage for emergency water purification.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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In emergencies where safe drinking water is unavailable, household liquid chlorine bleach can disinfect water and make it safer to drink. This calculator provides CDC and EPA sourced dosages so you get the exact amount right every time.
- Enter the volume of water you need to treat. You can use gallons, liters, or quarts.
- Select your bleach concentration. Check the label on your bleach bottle. Most standard household bleach is 6% sodium hypochlorite. Newer concentrated formulas are 8.25%. Do not use bleach with added cleaners, scents, or "splashless" formulas.
- Check the cloudy water box if the water appears murky, discolored, or has visible particles. Cloudy water requires double the bleach dosage. If possible, filter cloudy water through a clean cloth before treatment.
- Read your dosage in drops, teaspoons, or milliliters. Use whichever measurement is most practical.
- Start the 30-minute timer. After adding bleach, stir and wait 30 minutes. The water should have a slight chlorine smell. If it does not, repeat the dosage and wait another 15 minutes.
Boiling is the most reliable method when possible: bring water to a rolling boil for 1 minute (3 minutes above 6,500 feet elevation).
About Water Treatment with Bleach
The CDC and EPA recommend using regular, unscented liquid household bleach for emergency water disinfection. For 6% bleach, add 8 drops per gallon of clear water or 16 drops if the water is cloudy. For 8.25% bleach, add 6 drops per gallon of clear water or 12 drops if cloudy. After adding bleach, stir the water and let it stand for at least 30 minutes before drinking. Properly treated water should have a faint chlorine odor. This method kills most bacteria and viruses but may not be effective against all parasites. When possible, boiling water for 1 minute (3 minutes at elevations above 6,500 feet) remains the most reliable purification method.
Frequently Asked Questions
How many drops of bleach per gallon of water?
For 6% bleach, add 8 drops per gallon of clear water. For 8.25% bleach, add 6 drops per gallon of clear water. If the water is cloudy, double those amounts: 16 drops of 6% bleach or 12 drops of 8.25% bleach per gallon. These are the official CDC/EPA recommended dosages.
How long should I wait after adding bleach to water?
Wait at least 30 minutes after adding bleach before drinking the water. After 30 minutes, the water should have a slight chlorine smell. If you cannot detect any chlorine odor, repeat the dosage and wait an additional 15 minutes. If the water still does not smell faintly of chlorine, discard it and find another water source.
Can I use any type of bleach to purify water?
No. Use only regular, unscented liquid household bleach that contains sodium hypochlorite as the active ingredient. Do not use color-safe bleach, bleach with added cleaners or fragrances, "splashless" bleach, or bleach labeled for industrial use. Check the label: it should list either 6% or 8.25% sodium hypochlorite. Bleach loses potency over time, so use bleach that is less than one year old for best results.
Is boiling or bleach better for water purification?
Boiling is the most reliable single method for killing disease-causing organisms. Bring water to a rolling boil for 1 minute (3 minutes at elevations above 6,500 feet). However, bleach treatment is an effective alternative when boiling is not possible. Bleach kills most bacteria and viruses but may not eliminate all parasites such as Cryptosporidium. In situations where you cannot boil water, bleach disinfection is the recommended backup method per the CDC and EPA.