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Water Purification Using Chemicals

In times of emergency or natural disaster, clean water sources often become scarce.  However, it is possible to retrieve water from lakes, streams, ponds, and various other sources.  In circumstances where you have to draw from one of these sources, you will need to know various water purification methods.  This article will go over the chemical methods for treating contaminated water.

There are two types of chemical treatment: those using iodine and those using chlorine. If you purchase products specifically designed for this method, pay special attention to the directions and the expiration date.  Many of the tablets have an expiration date and become ineffective after that point. Also, once the bottle has been opened, the tablets must be used within a certain period.

General Chemical Treatment Procedures

  • The effectiveness of all chemical treatment of water is related to the temperature, pH level, and clarity of the water. Cloudy water often requires higher concentrations of chemical to disinfect.
  • If the water is cloudy or filled with large particles, strain it, using a cloth, before treatment. Large particles, if swallowed, may be purified only "on the outside."
  • Add the chemical to the water and swish it around to aid in dissolving.
  • The water should sit for at least 30 minutes after adding the chemical to allow purification to occur. If using tablets let the water sit for 30 minutes after the tablet has dissolved.
  • The colder the water, the less effective the chemical is as a purifying agent. Research has shown that at 50° F (10° C), only 90 percent of Giardia cysts were inactivated after 30 minutes of exposure. If the water temperature is below 40° F (4° C), double the treatment time before drinking. It is best if water is at least 60° F (16° C) before treating. You can place the water in the sun to warm it before treating.

To improve the taste of chemically treated water, try pouring it back and forth between containers, after it has been adequately treated. This allows more oxygen to get into the water, thus improving taste. 

Iodine Treatment Procedures
Iodine is light sensitive and must always be stored in a dark bottle. It works best if the water is over 68° F (21° C). Iodine has been shown to be more effect than chlorine-based treatments.  However, iodine may not be as readily available to you as common household bleach.

  • Liquid 2% Tincture of Iodine Add 5 drops per quart when the water is clear. Add 10 drops per quart when the water is cloudy.
  • Polar Pure Iodine Crystals Fill the Polar Pure bottle with water and shake. The solution will be ready for use in one hour. Add the number of capfuls (per quart of water treated) listed on the bottle, based on the temperature of the iodine solution. The particle trap prevents crystals from getting into the water being treated. It is important to note that you are using the iodine solution to treat the water, not the iodine crystals. Let the treated water stand for 30 minutes before drinking.  The water can be warmed in the sun before treating or hot water can be added. Refill the treatment bottle after use so that the solution will be ready one hour later. Crystals in the bottle make enough solution to treat about 2,000 quarts. Discard the bottle when empty.
  • Potable Aqua is an iodine tablet product. Follow the manufacturer’s instructions for use.

You should keep a copy of water purification methods in your emergency supply kit.  When disaster strikes you want to be prepared.  Water is essential to health so make note of these methods – they may save your life.