You all know the problem. No matter how you clean the heads when leaving the boat, when you return the first use smells like rotten eggs. I have at found the perfect solution.

Ok first off, the cause. It doesn't matter how much fresh water you do the final flush with, there is always salt water between the hull fitting & the heads pump. When the hull fitting is closed the bacteria in the salt water die and decompose...this is the cause of the smell when you next use the heads.

My solution is amazingly simple using two Y pieces, some tube & and in line valve. The plumbing involves fitting a Y piece to the drain of the heads SINK, this branch with the in line valve runs down to the second Y piece fitted as close to the hull fitting on the heads inlet as possible. When it comes to leaving the boat you close both the heads and sink hull fittings and then open the in line valve. You then fill the sink with FRESH water which can now be pumped out through the heads and hey presto no salt water in the system and no more smell....genius :)