Safe Storage of Emergency Water Supply?

[jenny_islander]

I am responsible for our family's shelter-in-place plan. (We live in a town that was smashed by a tsunami a few years before DH was born and has had many near misses since then, so we want to be ready for the next one.) I recently discovered that my family's emergency water supply is unsafe! I have to replace it all on a shoestring budget. My Google-Fu brought up directions from the North Carolina Cooperative Extension Service for choosing and cleaning recycled home water containers, so that part is covered.* The page includes directions for adding common household bleach to stored household tap water in a proportion that will stop any bacterial growth without poisoning the drinker. Unfortunately, the directions call for 5.25 percent bleach, which apparently is the kind commonly sold in stores--except that all of the stores in my town sell 6 percent bleach--and I live on an island, so driving to the next town is not an option. Google availeth me naught on this issue. Does anybody out there have directions for safely using 6 percent bleach to prevent bacterial growth in stored water?


*No, my state doesn't provide the directions in any publication I've been able to track down. I have no idea why.