What is that through hull for?

[Waterborn]

I recently purchased a 1995 Benny 281. I am trying to figure out what the through hull fitting is for that is located on the floor of the head. No no that one, beside the head intake fitting. The hose runs out through the bulkhead into the outside storage compartment.
Any ideas? It's leaking and needs replacement.

 

[Bill C320 Papillon]

There are two through hull fittings in the head. One is the raw water intake for flushing and I think other one is for overboard discharge. Look in the cockpit lazarette and see if you can follow the hose to the "y" valve that directs flushes either to the holding tank or to the hose through the aft head bulkhead.