Folks in such a place as there might be water restrictions - I would not live under such a tyranny in the first place - But if you must, you would likely be surprised at what a cistern catching the rain gutter will do. Now, I ain't in a place where water is a problem, but I know plenty of folks back in the sticks that cant get to a well - Drilling is a bit of a crapshoot up in the mountains, but one thing is sure - It WILL cost you 10s of thousands to try.
So there are a lot of dry homesteads that rely wholly on spring and summer rains (winter yields little as everything is frozen) With catchment ponds and cisterns holding thousands of gallons, all from rain on roofs and runoff.