Bleach Dosing Quick Reference (6-8.25% Sodium Hypochlorite)
| Volume | Clear Water | Cloudy Water | |---|---|---| | 1 liter | 2 drops | 4 drops | | 1 quart | 2 drops | 4 drops | | 1 gallon | 8 drops (1/8 tsp) | 16 drops (1/4 tsp) | | 5 gallons | 40 drops (1/2 tsp) | 80 drops (1 tsp) | | 55 gallons | 1/3 cup | 2/3 cup |
Contact time: 30 minutes for clear water, 60 minutes for cloudy water
Smell test: Treated water should have a faint chlorine odor. No odor after contact time = repeat dose and wait 15 more minutes.
The bleach must be: Unscented, plain sodium hypochlorite, no added cleaners
Bleach Concentration and Dosing
The ratios above apply to standard household bleach at 6-8.25% sodium hypochlorite. This is the concentration of most major brand bleach (Clorox Regular, store brand equivalents).
If you don't know the concentration:
- Check the label — the active ingredient percentage is listed
- Older or degraded bleach of uncertain concentration: use the cloudy water dose and do the smell test
Concentrated/Ultra bleach (above 8.25%): Do not use. The precise dosing becomes difficult at home and there is greater risk of over-chlorinating to a harmful level. Stick to standard 6-8.25%.
Non-chlorine bleach: Does not work. Must be sodium hypochlorite specifically.
Pre-Treatment: Filter Before Treating
Turbid water reduces disinfection effectiveness. Organic particles and sediment consume the chlorine before it reaches pathogens.
If the water is visibly cloudy:
- Let it settle for 30 minutes
- Pour off the top clearer layer or filter through a clean cloth
- Then apply bleach at the cloudy water dose anyway (you may not have removed all turbidity)
Clear water is defined as: you can see through a jar of it clearly. If there's visible cloudiness, turbidity, or color, use the higher dose.
Temperature Factor
Cold water slows chlorination. Below 10°C (50°F), the disinfection reaction proceeds more slowly.
For cold water: double the contact time (60 minutes for clear, 120 minutes for cloudy). The dose stays the same — time compensates.
Storing Bleach for Preparedness
Bleach degrades over time. Sodium hypochlorite breaks down, particularly after opening and in warm storage.
- New bleach (just purchased): full strength — use standard dose
- Bleach 6-12 months old, stored at room temperature: reduced potency — use cloudy water dose regardless of clarity
- Bleach older than 12 months: may be too degraded to rely on for disinfection. Do the smell test. If treated water doesn't smell faintly of chlorine, the bleach may be too old.
Better long-term storage alternative: Calcium hypochlorite (pool shock at 68-78% sodium hypochlorite) in granular form. Sealed and stored in a cool, dry location, it maintains potency for 10+ years. To make a liquid disinfectant from pool shock:
- Dissolve 1/4 teaspoon of pool shock in 2 gallons of water to make a 1% stock solution
- Use this stock solution at the standard bleach dose (8 drops per gallon) to treat water
Do not add pool shock granules directly to drinking water. Always make the intermediate stock solution.
What the Smell Test Actually Tells You
A faint chlorine odor after the contact time confirms that residual chlorine remains in the water — meaning enough chlorine was added to disinfect AND there's still some left over. This is the indicator that works.
No smell after waiting = one of two things:
- There wasn't enough chlorine (organic load consumed it all, or bleach was too weak)
- The contact time wasn't long enough
Repeat the dose. If still no smell, the water is likely too contaminated or the bleach too degraded for chemical treatment to work reliably. Switch to boiling.
Strong chlorine smell (chemical, overwhelming) = over-dosed. Pour off half the water and add fresh water to dilute, or simply wait — chlorine dissipates over time if left uncovered.