CisternWhen the concrete floor was designed and engineered there was appropriate concern for what to do when the ground water would heave.  Those who designed the original floor solved the problem with a fourteen-foot diameter by fourteen-foot deep cistern just outside of the turn around area.  Fed by a natural spring, this water has moderate hardness, and so far all of our testing shows it to be so clean we ought to be able to drink it straight out of the ground.  Considering the high chlorine levels in tap water, we have considered tapping it, but out of concerns for our own discipline in testing it, and the initial expense of adding such plumbing, we haven’t done so yet.  We have, however, used it to fill a swimming pool.  When we did, the water level returned to normal the same day.