Hurricane Response Guide for Environmental Public Health Professionals
If you do not have bottled water, you can make your water safe to drink by: Boiling water to kill bacteria, viruses, and parasites. Boil for 1 minute (or 3 minutes at elevations above 6,500 ft). Disinfecting water to kill most viruses and bacteria. Add 8 drops (or a little less than 1 / 8 of a teaspoon) of 5% - 9% unscented household bleach to 1 gallon of water. For cloudy tap water, use 16 drops (or ¼ teaspoon). If you do not have household bleach, chlorine dioxide tablets or iodine can be used according to label instructions. Disinfecting Water with Bleach Volume of Water Amount of 6% Bleach to Add* Amount of 8.25% of Bleach to Add* 1 quart/liter 2 drops 2 drops 1 gallon 8 drops 6 drops 2 gallons 16 drops ( 1 / 4 teaspoon) 12 drops ( 1 / 8 teaspoon) 4 gallons 1 / 3 teaspoon 1 / 4 teaspoon 8 gallons 2 / 3 teaspoon 1 / 2 teaspoon *Bleach may contain 6% or 8.25% sodium hypochlorite. Table adapted from EPA’s Emergency Disinfection of Drinking Water printout. Filtering water is another method that can remove parasites. Choose a water filter labeled to remove parasites and follow the manufacturer’s instructions. Filtered water might need additional treatment to be safe. Other Types of Disinfection Chemical processes used to treat water are described below:
Chlorine Gas
Calcium Hypochlorite Sodium Hypochlorite Chloramines
100% chlorine ion
65% to 75% chlorine ion
5.25% to 12.5% chlorine ion
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It is “technically” a liquid under pressure inside the cylinder, but it evaporates into a gas when released (at atmospheric pressure).
Calcium hypochlorite (HTH) is a powder (granular or tablet) form of chlorine.
Sodium hypochlorite is a liquid and can vary from 5.25% (laundry bleach) to 12.5% (commercially available) chlorine ion.
Chloramine is produced by combining chlorine and ammonia. It is a weaker disinfectant than chlorine, but it is more stable and longer lasting. It is often used to maintain drinking water at approved residual levels.
In addition to boiling and chemicals, distillation, ultraviolet light, and ozone can be used.
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