Pipe in fresh water
I piped in a fresh water supply from the head sink to the head. It has a valve. We can use potable water to flush or sea water via its own separate valve.If we use sea water, we can clear the line with fresh water before closing up. If we are not rationing water 100%, we flush with fresh water. Since sea water is loaded with minerals, using fresh water is alleged to reduce scalling inside the line, which greatly aid in reducing the process of odor permeation to the outside of the hose. We have had great success with it.Basically, I put a tee in the sink drain. I ran a hose to the feed to the head, connecting with another tee. This line needs a valve. When we want to flugh with sea water the fresh water valve stays closed, the sea water valve is opened and the sink drains as designed.When we want to flush with fresh water the sink drain is closed and the fresh water valve is opened.If is sounds complicated it is not really that bad. Also, there is no direct connection between our potable water and the head, since it is tied in to the sink drain only. I ordered all of the fittings and valves online at a brass fitting site. It took about an hour to do the install, including a 1" hole in the side of the sink cabinet.Good luck,Mike D