Re: Drinking water tank water.
We do carry some bottled water, and will drink that if we're drinking a glass with a meal, for example, but we use our tank water for coffee, tea and other hot beverages as well as washing up, of course.
We use a Brita faucet filter, and everything we drink goes through that. Since the filter is selectable, we don't waste filter life on wash water and water not intended for consumption.
There's no filter in the head so we use tank water directly for brushing teeth with no ill effect to date...
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"