Joel it is very easy. Toilets do not know the difference between flush water types. I have a 2006 H38 and converted over to having an option of fresh or raw water. All I did was tee off of the bathroom wash basin thru hull into a shuffle pump and ran it into a 3 way valve under the bathroom sink. I will use fresh water in the marina and will flip it to salt water after leaving the marina to conserve my fresh water. I did this conversion 5 years ago and have not had a problem. I even ran a blue poly line to the anchor well for an anchor wash down using a quick connect marine hose fitting. Allan