Better yet stock up on Calcium Hypochlorite. You can treat your water and make gallons of clean solution from just a pound of it!
I bought some of this years ago for this very reason. I stuck it up in a metal cabinet and left it there. Years later, I open the cabinet, and the corner where the Calcium Hypochlorite has been sitting is now rusted. Almost to the point of rusting through, even though the opposite end of the shelf is just fine. I'm reasonably sure it is a reaction between the shelf in the cabinet and the Calcium Hypochlorite.
Other than "stick it on a plastic shelf", does anyone have a suggestion for storing this stuff? If I put it inside a Zip-lock bag (or maybe several layers of Zip-locks), will that keep this from happening again?
Or, could it be that I'm blaming the wrong thing for forming the rust on the shelf?