When I installed a new head in my old boat a few years back, it was in the water so I was not able to install a through hull for the intake. I substitued raw water with water from the head sink that I just dumped in with a glass which worked great. Running some tests with my new head, I noticed that when I set the intake hose into a bucket and went through a cycle, it used an awful lot of water and it seemed to me that was only going to fill up the tank faster. Assuming the vast majority of head uses are urine, what is the down side of turning off the intake and just rinsing the bowl with a glass of water out of the drinking tanks? Obviously, one will need to fill water tanks a little more frequently, but beside that?Head odors can eminate from the intake and this would be one way to eliminate that problem.