IIRC, the Braggs had an artisian well. Ground and water pressure apparently forces the water to the surface in those kinds of wells, no moving parts, but pressure can be funny at times. (I know someone who has one, he kabitzes about the pressure all the time.) In the book there was apparently enough for them to use it for irrigation, so running it into household plumbing should be easy enough, so long as you stick to the ground floor.

Uhm, yeah, I kinda read the cover off a copy of Alas Babylon when I was younger.