Where is the head intake line plumbed to? Is it below the water line?
If it isn't below the water line, this can be a problem, especially if you have it plumbed to the sink drain.
Do you have an anti-siphon loop in it?
The anti-siphon loop is supposed to go between the pump and the bowl, not the pump and the through-hull.
It would help if you said what make/model head and sailboat you had. More specific information is generally better than less...
If it isn't below the water line, this can be a problem, especially if you have it plumbed to the sink drain.
Do you have an anti-siphon loop in it?
The anti-siphon loop is supposed to go between the pump and the bowl, not the pump and the through-hull.
It would help if you said what make/model head and sailboat you had. More specific information is generally better than less...
