This is slightly off the topic of the thread but I was thinking about
Donny's water issue and came upon an idea. This won't help Donny, like I
said it's a little off topic.

On my house I have a "whole house" water filter inline in the 3/4" pipe that
enters into the basement. Before the water forks off to the hot water tank
and the other myriad destinations it runs through an activated charcoal
filter. The filter doesn't seem to drop the water pressure at all and makes
a noticeable difference in the quality of the water (the water even feels
different, and we have good water to begin with).

I first got one of these when I lived in the country and we had really bad
water that tasted bad and left stains in the porcelain -- I don't want to be
too graphic but the water was also discoloured and the toilet always looked
as if it hadn't been flushed.

Anyway, the thing was $50 from Canadian Tire and it made a tremendous
difference. It's not often I find a product that works as well as I had
hoped. After installing it you could drink the water right out of the tap, I
can only imagine how many years of life it added to my hot water tank.

So reading this thread it occured to me that it would be a simple thing to
rig a dockside equivalent.

Dockside water hose in one side -- filter rig -- outlet hose to fill the
water tank in the boat.

If you were particularly handy you could make a nice housing for it and
perhaps a method to clip it to a cleat.