Shared bilge pump discharges?

[rwthomas1]

The shower drain pump and the bilge pump share a thru-hull on my boat. They are joined with a T fitting. I am guessing that this is not optimum. I am thinking they should have dedicated thru-hulls. Issue is I already have plenty of holes in the transom. 2 cockpit drains, 2 propane locker drains, 1 exhaust and 1 bilge. What say the crowd? Keep the T or drill and other hole? Shoulda made this a poll..... RT

 

[Chris A.]

Rob,

I agree that it isn't optimum. Is your shower sump a diaphragm pump? If so I think the shower drain line is less likely to have backflow problems when your bilge pump is running. I don't know about backflow on your centrifugal (?) bilge pump when your shower sump is running. Rule sells a Y connector that, if you mount it in a high place and near the through hull, will decreases the likelihood of backflow in either direction, IMO.

I have a diaphragm bilge pump plumbed together with a diaphragm shower sump pump in this fashion. I have a separate centrifugal bilge pump plumbed with a vented loop and it's own through hull.

Y fitting link

I didn't want to add yet another through hull either!

Cheers,