When you put things back together, replace the tee that connects the head intake line to the cold water line with a shutoff valve, so you won't have to turn off the water to the whole boat to work on the toilet.
Or, if the connection isn't in an easily accessible location, add a shutoff valve in a location that is.
© 2016 Peggie Hall
Specializing in marine sanitation since '87.
Author"The NEW Get Rid of Boat Odors"