When I bought my old boat both toilets were manually operated, and they constantly leaked. I replaced them with full size electric heads and this long article explains how they were fitted, along with a United States Coast Guard waste treatment system that makes a holding tank unnecessary. The article also shows how to make the toilets flush with fresh water, that stops the foul smell associated with seawater toilets.
1519 words 7 pictures. Price for this article $10
SALT WATER AND FRESH WATER FLUSH