in our applications, but I was reading about a woman (my hero) who almost singlehandedly built a concrete water tank on her property. Here's the link to the whole article

http://www.backwoodshome.com/articles2/ainsworth101.html

The part of the article that applies to us'ns follows:

I think the reason my tank has held up so well for 23 years now, in spite of the 1:3:5 "poormanÂs mix" I used, is because I coated the inside of the tank with a cohesive sealer called "Thoroseal."

Thoroseal is a Portland-cement-based coating that, when mixed with a milky-looking catalyst called Acryl 60, fills and seals voids and waterproofs the concrete. It prevents any water seepage from leaking into fissures where it might freeze and expand and crack the concrete. It also resists hydrostatic pressure (as inside a water tank) and is non-toxic in potable water tanks. It can be brushed on, but Bill advised me to trowel it on about 1/4" thick for an impenetrable bond. It took a lot of elbow grease applying it in smooth swipes on the entire inside surface of the tank, but it covered up all those rough cold-joint seams and made it look as smooth and beautiful as a baby-elephantÂs butt.

Dorothy Ainsworth is a VERY self-sufficient woman. You can check out previous articles by and about her on Backwoods Home mag's site. She built 2 (yes, 2) cabins with logs she hauled in from the forest. The first one burned down before she could finish it, then she took a deep breath and went ahead and built another one. My hero.

Jo