Letter Re: Caustic Chlorine Troubles, and Using Dry Chlorine for Water Treatment

Dear Jim:

As you know, ordinary chlorine bleach is an item with a multitude of potential uses in survival situations. In addition to its common use in the laundry to brighten our whites, it can also purify drinking water and serve as a general disinfectant to sanitize food preparation areas and control the spread of disease causing bacteria.

Liquid chlorine bleach, however, is inconvenient to store. Only about 5.25% – 7.5% of each eight pound gallon is active sodium (or calcium) hypochlorite; the rest is just water. Yet because of the potency of its active ingredient, and the flimsiness of typical plastic bleach bottles, it poses a constant risk to everything stored near it.

One potential solution is to store concentrated dry chlorine granules; commonly available as swimming pool shock treatment. Available in a wide variety of sizes, swimming pool shock treatment typically contains from 50% – 60% active calcium hypochlorite, making it much lighter in weight and 10 times as concentrated as liquid bleach, but not susceptible to spilling and leaking risks. Theoretically, it should be possible to make your own chlorine bleach by simply combining the proper amount of water and dry granules.

I quickly discovered, however, that storing dry chlorine poses hazards of its own. Initially, I purchased two 1 pound plastic bags of swimming pool shock treatment and stored them in a small closet along with a variety of other preparedness items. The granules generated a strong chlorine smell in the closet, but when access was needed, opening the door for a minute or two would reduce the small to a tolerable level.

About a year later, however, I went to reorganize the closet, and was startled to find many things badly corroded by fumes from the granules. Several storage tins were badly rusted, some 200-hour emergency candles in tins were nearly rusted clear through, and the steel ends of some batteries were also corroded.

Surprisingly, even some lightweight cardboard boxes were so badly degraded that they virtually disintegrated when handled, and a 10-page document (about emergency water) which had been printed on our computer’s inkjet printer was virtually erased!

To combat these problems, I bought a fresh supply of (HTH brand $3.35/lb. at Wal-Mart) chlorine granules and stored them in an all-glass canister with a glass top, rubber ring, and spring wire snap latch ($4.44 at Wal-Mart) . That has solved my storage problem.

In an article on emergency water purification, in addition to the old 10 drops of bleach per gallon of clear water or 20 drops per gallon of cloudy formula; I found this recipe for using granular pool chlorine:
For use in purifying drinking water, first prepare a stock solution of one heaping teaspoon of granules dissolved in two gallons of water. This may then be mixed at the rate of 1 part
stock solution to 100 parts water for disinfection purposes. That would equal: 1 quart for 25 gallons, 6 1/2 ounces for five gallons, or 2 Tbsp. per gallon.

Jim, I wish you could help me find out: How much dry chlorine would be needed to make a one gallon batch of standard 5.25% chlorine bleach? I haven’t been able to find that information anywhere! These HTH granules are 54% calcium hypochlorite. Perhaps you or one of your chemistry-savvy readers could figure-out the correct formula. Sincerely, – Steve W

JWR Replies:

It is best to keep your sodium hypochlorate in powdered form until just before it is used. Once it is put in solution, it weakens over time. This can create confusion about its remaining concentration when it is eventually used to treat water. Back in June of 2007, SurvivalBlog reader Terry M. kindly provided some useful details on treating water with both commonly available forms of hypochlorate powder. Perhaps some readers would care to chime in about the dry measure required for making each gallon of liquid bleach. (I’m not a chemist!)