In my 2005 Journey there is a SurFlow 3 chamber water pump that runs when the pressure drops below some predetermined point. The exact point is unknown to me but probably something like 20 to 30 PSI. If the system is tight, meaning no leaks at all, it will not come on without opening a faucet or flushing the toilet. If there is a tiny leak, it will come on briefly every hour or so. I lived with the tiny leak scenario for two years but then it began to run nearly continuously and air would spit from...