I was pondering my own cheap water supply, and I have a rather nice advantage.

I have this in my back yard, spring fed, year-round:


That's about 127,170 gallons of water, and it's very much able to be processed quickly and easily into drinking water. I know, because I've done it. It tests fine for all of the bad stuff.

In the house, I have a 75 gallon hot water heater and a 50 gallon cold water tank that are always full, since that's my domestic water supply.

I'm fed by a well 400' deep, according to the well driller, the water starts at 40' down and just keeps on going. I can and have pumped 10 gallons a minute from the well for 24 hours straight (this was during a draw-down test).

Yay rural living!