How to Install The Seaflo Raw Water Electric Marine Toilet Macerating in A fifth Wheel

Updated 07/12/2026 | Published 02/20/2026

Question:

Is there an adapter available to cover the large 3inch hole toilet flange in my 5thwheel with the outlet sized hose from this toilet? Or how would you run the small 1inch diameter outlet hose from this macerating toilet to the large 3inch toilet flange?

asked by: Richarge

Expert Reply:

Great question! Macerating toilets like the Seaflo do not connect to the standard 3-inch RV floor flange like a traditional gravity toilet does. That flange is designed for toilets that drop waste straight down into the black tank. A macerating toilet works differently it grinds the waste and pumps it out through a 1-inch to 1-1/2-inch discharge hose instead. Because of that, the toilet doesn’t seal to the flange at all. Instead, you would cap or seal off the existing 3-inch flange opening with a mechanical test plug or glue a cap over it to prevent tank odors from coming up, then run the discharge hose directly to a proper inlet fitting on the black tank.

For installation, the toilet simply bolts to the floor using the mounting holes in the base, similar to how a residential toilet mounts, but without using a wax or foam ring. You’ll pre-drill pilot holes and secure it with stainless screws or bolts for stability. From there, connect the discharge hose to the tank using proper sanitation hose and clamps, and wire the unit to a fused 12V power source per the instructions. So it’s more of a pump-style installation than a direct drop-in replacement, but it works great when plumbed correctly.

expert reply by: Heather A

Brian

7/12/2026

The response to the install question says "then run the discharge hose directly to a proper inlet fitting on the black tank." This is not practical on any RV I have seen. There are only 3 inlet fittings on a black tank. There is the 3" fitting where the toilet sits, there's the vent pipe going up to the roof, and then there's the 3" discharge on the outside of the RV. Ideally there would be a way to route the macerator discharge down the existing 3" hole through an adapter but that doesn't look practical to me. You could possibly put the discharge in the vent pipe if you can access it. Otherwise you would have to remove the black tank and take it to shop that has equipment to add an additional fitting for the discharge tube. Note: I really like the idea of the macerating toilet as it uses a fixed amount of water per flush. This would take out all the guess work in determining the level of the black tank. You could count the number of flushes instead of using the level sensors which are worthless.