Steve Lusardi wrote:
Peggie,
Thank you for your reply. No, I have no intention of combining black and
grey water. The application is a sailboat. Sailboats live on their ear. All
drains are effectively below the waterline. In that light, draining through
conventional water traps into a large grey water tank with one through hull
and a single pump and check valve allow facility useage under all points of
sail in all weather conditions. To me, this is highly desireable and is a
better solution than shutting all outboard drains in heavy weather. This
solution is not available to all designs. There must be adequate headroom
and bilge depth to facilitate it.
Steve

I don't know Steve, it does depend on the boat and the location of the
sink. Our galley sink (well outboard under the side deck) on our 30'
monohull would fill slightly if the boat spent hours on one tack in
rough weather (heeling more than normal). Never enough to get on the
counter though.

The head sink was closer to centerline and never saw a drop from
heeling. Sinks closer to centerline are much better in this regard.

Oh if you do fit a sump tank, make sure you have a means to clean it
out often. Our shower sump tank got really funky when we showered
regularly.

Evan Gatehouse