The area where we will make an eventual move to is quite dry. People collect rainwater. I don't think it is illegal.
A couple of years ago, when I had huge aspirations of becoming a beeekeeper that would get hundreds upon thousands (well, maybe exaggerating a little here) I purchased a huge stainless steel honey tank, with of course a 2" honeygate. I was going to fill that honey tank, but just never got around to doing it, hee, hee. It will accompany us on our move and will be a holder of great amounts of water. I wish that I knew how many gallons it holds -- it is a pretty big tank. I would imagine that there is some mathematical equation like measuring depth circumference and then multiplying something with something that would give the volume. Maybe one day I will entertain that work and figure it out. I would have to write it somewhere so I don't forget and have to do that work again. Oh, maybe just a piece of tape on the outside of the tank with the information -- oh I am so smart, hee, hee, I think of such cool things, hee, hee. Silly me. Have that great, most wonderful day, to love and live our beautiful lives, great health. Cindi