Originally Posted by sailingdog
I believe the water intake was left off the drawing to simplify it... and not confuse the novice boat plumbers...
This setup with the modifications I've indicated is designed to allow flushing into the holding tank or directly overboard, as well as pumping out the tank via the pump used to flush the Lavac head, or via a deck pumpout fitting. It is also designed to only require one pumpout fitting or connection on the holding tank.
Then it's identical to mine. My only modification, which I may or may not pursue, is to use the Henderson as a manual sump pump for an as-yet-designed shower stall. I would have an electrical bilge pump as a matter of course, but I wouldn't want my "fail-safe" to be a bucket and sponge if the sump pump packed it in.