We have a holding tank which deals with the wc in the heads. But galley sink and heads basin and shower all drain into the bilge (which is deep and about 2 cubic feet), to be pumped out with bilge pump above waterline. I'm sure that this will be impractical and smelly so I thought that if I made a box to fit into the bilge containing an electric pump with float switch - all this grey water could be automatically pumped into the holding tank. I envisage the box being sealed to prevent smells and as small as possible (just pump, float switch and about a pint or two) so as not to take up all of deep bilge.

Is this a practlcal idea?

PS - galley etc can't drain direct to holding tank