Is Dometic 411 RV Toilet Direct Replacement for Thetford Aqua Magic VI

Updated 06/15/2026 | Published 01/14/2026

Question:

Is this a direct replacement for the Thetford Aqua Magic VI?

asked by: Don

Expert Reply:

Hey Don, yes the Dometic 411 RV Toilet part # DMC74JF would be a direct replacement for the Thetford Aqua Magic VI as they both have the same rough in measurement. Is your Thetford giving you problems?

expert reply by: Jameson C

Don

1/15/2026

Thanks Jameson, Yes, it is causing problems for me. Though I’ve mitigated some of them. The Thetford Aqua Magic VI is a two part toilet. The upper Assy contains the bowl and the lower Assy is what mounts to the floor. The seam where these two parts join is a tongue and groove seam. Thetford does not seal this joint with a gasket or O-ring. This allows odor from the black water tank to escape into the cabin area of the rv. This is very noticeable when a window or vent is left open while driving. It causes a low pressure area to form and draws odor from the tanks up to the divers area. This also happens with the gray water tank but the odor isn’t quite as bad. The roof venting isn’t efficient enough while driving the vehicle to overcome the low pressure area caused by open windows or vents. I’ve even installed a Camco Venturi style vent and it’s not enough either. I was able to correct the problem by removing and disassembling the toilet and filling the tongue and groove with an RTV type sealant internally. I then reassembled the toilet and sealed the outside seam with the same RTV. This has completely eliminated any odor from the black water tank while driving with the windows open. Or, at any time actually. The Thetford toilet also feels quite flimsy. It flexes while sitting on it. It just doesn’t feel sturdy. This is why I’m looking for a more robust design. I’ve seen your ad for the Dometic 411 and it appears to be a better solution for this. The build design also prevents issues of odors escaping the toilet. Don.

Jameson C.

1/15/2026

@Don Makes sense! I know there's an older Dometic toilet that had a very similar problem. It's kind of crazy that both Thetford and Dometic had a similar issue.