I believe it is a bilge pump. I was given a plastic sump box and the pump was already in it.
I routed the pump down the top side of the bilge, through to the engine area, up under the galley to a vented loop, and down to the sink drain. Just make sure that the sink drain is open when you use the shower.
I found the float switch to be a pain in the butt. I put a water proof toggle switch inside of the head that mounts to some of the trim. It was a lot of running wires to do this but it was worth it. I flip the switch to on when I turn the water on to shower and turn it off a few seconds after I finished with the water.
My sump box has a mesh screen in it to sift out hair (this is important). You should clean it once in a while. The area to put the sump box is tight and I can't remember the dimensions. I would suggest getting the smallest box you can find unless you are good enough to make one.
