I like the idea, but the problem for me would be space. Hooking up more water heaters could be an issue. I don't know how house are built there, but here the water tank is in a fairly small closet.

Second, I wouldn't want to deal with someone elses discarded water tank...no telling what you could get into there and for $250 you can buy several food grade plastic drums in various sizes that are cleaner and moveable.

Just my opinion...but I do like the idea.