It seems pretty clear that there are no grey water systems for small boats,
though I've
wondered if it would be feasible to save shower water for deck washdown.
However, many
(most?) of the newer cruise ships do recycle gray water. They filter it to
"near drinking
water quality" and use it, not for drinking, but for cooling systems and
washing.

Thanks for clearing that up, Jeff. I had never heard of recycling grey water
for cruising boats. Even the mega yachts don't seem to have it. This exists on
Princess Cruise line ships and the like?

RB