Minus the cost of materials, can't beat FREE water!
Also, seems like the most important aspect always boils down to filtering and purification. Any recommendations there? Lately, I've been thinking about getting a Berkey water filter for the kitchen. I looked around at tons of other options, from whole house filtration systems, to portable/semi-portable types like Berkey's, but there are too many options to choose from.
I've just got my water filters from my hiking daze. A lot of work to get a liter of water and it just removes most parasites in the water, not chemicals (which is why I ask about about how to clean the pool water).
I suppose the first question I should ask is how much I can realistically keep on hand, how to store it and how long it will last.