Question
We lost old house to Katrina; rebuilt a new one using "green" technologies. We had extra cinderblocks so our green expert built our rainwater irrigation cistern with them and sealed the inside with state-of-the art I'm not sure what.  Looks like shiny white paint and the water is supposedly potable. Problem is, the cistern leaks (slow) at the bottom edge all around. Since one wall of the cistern is also the inside wall of our lower enclosed storage, we always have wetness in our enclosed storage area. Cistern is 15' x 5' x 3.5', and only has one opening on the top for access. We're out of money and our green expert ignores us. We heard we have to coat the inside with a nasty epoxy-like stuff that is poison to breathe, or put in some sort of bladder. Both options are expensive and with only one small access, anyone who goes in there would die of exposure to the epoxy fumes (if we use the epoxy option). Maybe we need to ditch the cistern and use city water?

Answer
I personally have no experiance with this kind of project, but I poked around a little and came up with report from a fellow who built his cistern with concrete, and sealed the interior with a mixture of portland cement and an additive.  Below is the webpage where I found the report.

http://www.dancingrabbit.org/building/cistern.php