Purify Drinking Water With Bleach – How Much To Make It Safe
I’m going to tell you how much bleach to purify water. I have updated this to include bleach with 8.25% sodium hypochlorite (as the active ingredient). There are several ways to help make water safe to drink including boiling and filtration (see below). Regular household bleach is just one other method. Note that we’re talking about purifying for organic pathogens (the most common reason for purifying water). However this will not mitigate toxic chemicals that may be in the water (uncommon).
Boiling Water. First, I would be remiss if I did not say that one best way to treat water for drinking is to boil it first. It only has to boil for about one minute. According to the Wilderness Medical Society, water temperatures above 160° F (70° C) kill all pathogens within 30 minutes and above 185° F (85° C) within a few minutes. So in the time it takes for the water to reach the boiling point (212° F or 100° C), all organic pathogens will be eliminated, even at high altitude.
Another effective way to make water safe to drink is to add a specific amount of regular household bleach. Depending on brand or concentration, regular household bleach contains between 5.25 and 8.25 percent available chlorine (liquid sodium hypochlorite), which will disinfect the water if added in the right amount. So, again, how much bleach to purify water?
How to purify water with Bleach: If the collected water to be treated is cloudy and contains sediment, either scoop a new sample with less sediment, or strain it first through a makeshift filter (cloth bandana, t-shirt, coffee filter, etc..) or let it sit in the container allowing sediment to settle to the bottom. Gently pour off the clearer water on top. Use regular liquid household bleach (any brand); however the only active ingredient should be sodium hypochlorite. Do not use bleach that contain soaps, perfumes, or dyes. Be sure to read the label.
‘CDC’ instructions for safe drinking water with bleach: From the CDC, Centers for Disease Control, “If you don’t have clean, safe, bottled water and if boiling is not possible, you often can make water safer to drink by using a disinfectant, such as unscented household chlorine bleach”
How much bleach per gallon of water. Add 1/8 teaspoon (or 8 drops; about 0.625 milliliters) of unscented liquid household chlorine (5–6% sodium hypochlorite) bleach for each gallon of clear water (or 2 drops of bleach for each liter or each quart of clear water). There are 3.78 liters per 1 gallon.
(5 drops using bleach with 8.25% sodium hypochlorite for 1 gallon) Stir the mixture well. Let it stand for 30 minutes or longer before you use it.
5-6%=2 drops/liter for clear water. . 4 drops cloudy water. 8 drops/gallon clear water. 16 drops for cloudy water/gallon.
825%=5 drops/gallon clear water.
How much bleach to purify water if it’s cloudy with sediment. Add 1/4 teaspoon (or 16 drops; about 1.50 milliliters) of bleach (5–6% sodium hypochlorite) for each gallon of cloudy water (or 4 drops of bleach for each liter or each quart of cloudy water).
(10 drops using bleach with 8.25% sodium hypochlorite) Stir the mixture well. Let it stand for 30 minutes or longer before you use it.
Rule of thumb… After initial dose, smell the water. If the water has a faint smell of chlorine, then it’s okay to use. If you cannot detect any chlorine odor, add another 8 drops of regular liquid bleach. Let stand, and smell it again. If you still cannot smell chlorine, discard it and find another water source.
We’re looking for 1, 2, or 3 ppm (parts per million). Chlorine test strips (or swimming pool test kit for chlorine) are useful to verify the chlorine level in the water. The maximum ‘safe’ level for drinking water according to the EPA is 4 ppm.
Note that bleach has a shelf life, although you will probably not see a date on the bottle. Chlorine bleach may lose 20% to as much as 50% effectiveness within a year, so be sure to date your bottle upon purchase.
Notes about chlorine level for safe drinking water: The EPA recommends a maximum (no more than) 4 ppm (parts per million) of chlorine for safe drinking water. A typical municipal water supply measured at the home faucet is typically between 0.2 and 0.5 ppm chlorine. It takes 45 minutes to destroy Giardia Protozoan (common cause of diarrhea) with 1 ppm chlorine level.
‘WHO’ instructions for safe drinking water with bleach: From the WHO, World Health Organization, “Chlorine is commonly available to households as liquid bleach (sodium hypochlorite), usually with a chlorine concentration of 1%”. Disinfection with chlorine is the most appropriate way of ensuring microbiological safety in most low-cost settings. At least 30 minutes contact time should be allowed after the chlorine is added to the water before the water is drunk, to ensure adequate disinfection. The free chlorine residual (the free form of chlorine remaining in the water after the contact time) should be between 0.5 and 1.0 mg/l (0.5 ppm and 1.0 ppm).