• Background

Public Education

Post Disaster Water Treatment

In addition to having a bad odor and taste, water from questionable sources may be contaminated by a variety of microorganisms, including bacteria and parasites that cause diseases such as dysentery, cholera, typhoid, and hepatitis. All water of uncertain purity should be treated before use. To treat water, follow these steps:
  • Filter the water using a piece of cloth or coffee filter to remove solid particles.
  • Bring water to a rolling boil for about one full minutes.
  • Let it cool at least 30 minutes. Water must be cool or the chlorine treatment described below will be useless.
  • Add 16 drops of liquid chlorine bleach per gallon of cool water, or 8 drops per 2-liter bottle of water. Stir to mix. 5.25% sodium hypochlorite should be the only active ingredient in the bleach. There should not be any added soap or fragrances.
  • Let stand 30 minutes.
  • If it smells of chlorine, you can use it. If it does not smell of chlorine, add 16 more drops of chlorine bleach per gallon of water (or 8 drops per 2-liter bottle of water), let stand 30 minutes, and smell it again. If it smells of chlorine, you can use it. If it does not smell of chlorine, discard it and find another source of water.


Changes to past information:
The only agent to use for treating water should be liquid household bleach. Other chemicals, such as iodine or products sold in camping or surplus stores for water treatment that do not contain 5.25% sodium hypochlorite as the only active ingredient are not recommended and should not be used.

The only accepted measurement of chlorine (or water treatment agents) is the drop. A drop is specifically measurable. Other measurements such as "capful" or "scant teaspoon" are not consistent, and should not be used.