Re: Family sized swimming pools...
Second that. Ours, well, the one that came with the rented house, is 85,000 l. Close enough to 20,000 gallons.
It was interesting to work out because it's sort of a 90 degree triangle, but the hypotenuse is 'Z' shaped.
But we digress, as already stated, Olympice Size Pools is a safer measure.