All good comments, nevertheless I'll give it a try.
I'm putting a check valve in the FW line to prevent saltwater backflowing into the FW tank.
Re starving the engine
, I watched the exhaust
with the galley
pump running and there was no noticable decrease in water
flow out. In any case, I'd have to leave the galley
pump running for an awful long time to cause engine overheating
My sailing is coastal, and I have a completely separate FW tank, so even if I did contaminate the main tank, I've got a few days back-up and won't die of thirst.