on the other side of that wall, is the inlet from the well, it goes,
well,( from the well is plastic) to a presure tank (turns to copper at the T) after that it turns placis ageain, then it goes though the wall, to the water softer, witch is that big stand up thing, from here, it goes copper ageain, to the water heater.... inbetween the water softer, and the water heater is where my perce vavle is, the ro unit has a on off switch, (the inlet side of the on-off has water in it all the time) after that is where the water comeing in TDS sensor is. then it goes, though all 5 off the cans and out to the tank. This is were the filterd water is tested, the 2nd TDS sensor, is here and after the auto switch ,
i got the auto switch only so when i take a gallon or 2 out, i can turn it on, and not worrie about it overfilling if i wall away. but i dont recommend leaveing the water on to the ro tank all the time, or for any plumming in that case.
when the valve turns off cause its full, the water backs up in the DI cartregde's (witch i think is bad, cause with out the switch it will drain all out)