I wrote these instructions for storage with a bag of calcium hypochlorite "pool shock", along with measuring devices. This is based on what I've read on the web, primarily from Survival Topics. The idea would be that my older children or my wife would be able to purify water successfully without my help.

If you see any way for these instructions to be improved, I'd be grateful for your feedback.


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Water Disinfection Instructions

1) Filter the water. If the water is cloudy or has any suspended particles in it, filter it to remove as much cloudiness/particles as possible. Use a shirt, handkerchief, filter mask, or other field-expedient means if you don’t have a purpose-made water filter. Alternatively, allow the water to stand undisturbed so that the particulate matter settles – this could be as long as 24 hours. Then draw the clear water from the top. If this isn’t possible, move on to the next step.

2) Make a stock of chlorine solution. Dissolve one heaping teaspoon (about ¾ ounce) of calcium hypochlorite granuals into two gallons (eight liters) of water. DO NOT DRINK THE CHLORINE SOLUTION.

3) Add chlorine solution to water. Add one part of the chlorine solution to 100 parts clear water to be treated. For example, add 6.4 ounces of chlorine solution for five gallons (640 ounces) of water. Double the amount of chlorine solution for cloudy or colored water.

4) Agitate. Loosen the cap of the container and shake vigorously, allowing chlorine solution to mix thoroughly with the water to be treated, and allowing the water to splash onto the threads of the container and the cap so that no untreated water comes into contact with people, clean containers or treated water.

5) Let it sit. Let the treated water sit for at least thirty minutes with the cap on before drinking.

6) Check for chlorine odor. The water should have a slight chlorine odor; if not, repeat the dosage and allow the water to stand for an additional fifteen minutes.

7) Aerate (optional). If the treated water has too strong a chlorine taste, aerate by allowing the water to stand exposed to air for a few hours, or by pouring it from one clean container to another several times.

8) Drink.

The only addition I would make would be to point out that a smaller quantity of purified water can be prepared more quickly ( varying somewhat with circumstances) by boiling. A good backpacking stove can boil one liter in about four minutes.

Would the prevailing temperature affect the treatment time of the chlorinated water?

That's an excellent point. I will update the documentation accordingly.



According to http://www.water-research.net/watertreatment/chlorination.htm, "Contact time must increase under conditions of low water temperature or high pH (alkalinity)." Unfortunately, I don't seem to be able to find a cookbook that says how much more time at what temperatures.