[scottz]

Originally Posted by Johndavis

Yes it was hypothetical. What I didnt mention is that we are actually connected to well water at 40 psi and the flow at faucets, etc is puny unless pump is on. Pressure at faucets with pump off is ok for two seconds and then reduces to about half-flow; hence we leave pump on and pressure is good. But I was wondering if it is then using fresh water.

Got it, thanks for the explanation. Yes, in that case, you are using some of your on board fresh water.