Holding Tank T-fitting

I am currently replacing the old Galleymaid toilets with Raritan marine elegance ones. Two of the old GM toilets used the same holding tank fitting by sharing a t-fitting into the tank. Hopefully it's a stupid question, but is there any reason I cannot use the same fitting for the new toilets? My concern is that when I flush one toilet that uses the t-fitting, what keeps the effluent from going into the other hose and possibly backing up into the other toilet, rather than into the holding tank? I know the Raritans have joker valves that resist back flow, but is that enough?

As I say, hopefully a stupid question but I figured I'd ask the experts before proceeding. It wouldn't be that big of a deal to install another fitting on the tank, but I have enough work without creating more for myself over (hopefully) imagined problems.


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We have a " Y " looking fitting for our discharge so the flow isn't directly pointed at the other one.

Hello, I have two heads, one marine eleganze and one Raritan PHII. The discharge lines to the tank has a fitting called a T/Y in it to connect them. Never had an issue with flushing either head.

Walt Hoover

I used 1 1/2 hose when I ran I plumbed in the new heads. I had the same concerns so I epoxied in a fiberglass 1 1/2 fitting

I called Raritan tech support today and they said that, although the 90 degree t-fitting would work, it might put strain on the joker valves. The tech feared that as the joker valves wear over time one toilet might start to get seepage into the other one. He recommended a y-fitting or a dedicated fitting. I think I'll do what you did, Pete.

Thanks, everyone, for your responses.