I am in Tennessee and here on the river no one ever checks our boats for holding tanks. My boat is from the 70's and there was never a holding tank like most boats built before 1985 Sadly we dump in the river. I am installing a 140 gallon holding tank in my boat, not that I have but I want to. I am building my tank out of fiberglass in the engine room, that is the only way I can build one this size.
In the mid bathroom /head I wanted to use a RV style toilet/head they use so much less water. Sense they dump straight down I had to build a small tank under the head first, it holds eleven gallons. The small tank will dump into the lager 140 gallon tank like flushing a crown head, easy as pie.
Rv heads need no water to flush just to fill the bowl as in use, the work like a Vacuflush. In my master bath I have a atlantes head, i don't think I have the room to install a tank under my floor but maybe later I will look into it more. the front bathroom will have to wait too.
http://web.mac.com/tanyard/Site_6/bu...anks.html#grid http://web.mac.com/tanyard/Site_6/mid_bath.html#0 www.bigwoodenboat.com