[blam]

"* Don't count on a bottle of bleach, because it has a more limited shelf life than most people realize."

My son (PhD physics) says that 'store bought' bleach will lose about 50% of it's strength per year.

[The Duke]

That sounds about right. Here's the original article that got me started on this:

http://www.survivaltopics.com/survival/better-than-bleach-use-calcium-hypochlorite-to-disinfect-water/

Also, in a disaster situation, you may find yourself going through bleach quite a bit for basic sanitation purposes. Bleach is also critical in fighting cholera outbreaks.

Since calcium hypochlorite is used to make bleach, you you just can't go wrong with it (however, it's just as important to know how to properly store, handle and use it).

Also, it's important to buy it in 'granular' form, rather than in pellets (I suppose one could find a way to use the pelletized version in a pinch).

Also, when compare to gathering and using firewood to purify water think of the time, energy and risk you'll save using calcium hypochlorite(!)