Don:
For potable water on board, I use a GE filter (Home Depot) just downstream from the FW pump. (They are "quick disconnect" for easy annual changing.) I also use the Pure faucet filter at the galley sink as a secondary filter. To top it all off, I purchased a portable water tester (smaller than a pack of cigarettes), $50, at one of the chandlerlies for confirming the water quality. (Talk about anal, huh?)
Now, for your blue hull. I use GE Mobile Water, Inc, for rinsing down the boat. They put a deionized bottle at your dock box that your dock hose hooks on to and they change it either on demand (you call) or every 6 weeks, etc. whatever you deem necessary. After the deposite ($250) your bill is $17.40/ mo. (You get your deposite back after 6 months if you keep your account in good shape.) There are other companies that provide this same service.
I can't say enough about using DI water to rinse the boat down. Without wiping, the boat drys absolutely spot free. It's probably not needed on white hulls as the water spots are not so apparent.
These applications have served me well over the years and I can remember only one person that got sick. It was "dwhatty" but the empty Jack Daniels bottle may have been involved. (Just kidding, Dave!)
DI Bottle
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