Will the Thetford Aqua-Magic Style II be an Easy Swap Out Replacement for My Dometic 310?

Updated 11/20/2025 | Published 11/19/2025

Question:

I have a Dometic 310 in my Brinkley Z Air 295. Im outside of warranty and finding that the bowl is likely defective resulting in the bowl leaking... thought it was a bad seal but it must be the bowl as it keeps happening with new seals. Im looking to replace the entire toilet pending Brinkleys resolution. Would this Thetford be an easy -in replacement or might I have compatibility issues given I had a Dometic previously?

asked by: Scott

Expert Reply:

Hello Scott,

The Thetford Aqua-Magic Style II Part-Timer RV Toilet, part # TH49FR, will be a great replacement for your Dometic 310. Both toilets use the same standard two-bolt mounting pattern and connect to a 3-inch waste flange, so the installation process will be very similar.

One small difference is the rough-in measurement. The Dometic 310 requires about a 10-inch distance from the back wall to the center of the flange bolts, while the Thetford Style II only needs 9-1/2 inches. This means the Thetford will fit comfortably in place of the Dometic, with a little extra clearance behind it instead of being too tight to the wall. I attached an image to show what measurement I am referring to.

Before installation, it’s a good idea to check the height of your toilet flange above the finished floor. The flange should sit about 7/16 of an inch high to allow the floor seal to compress properly. To check this, measure from the floor up to the top edge of the flange lip. If it’s lower than 7/16 inch, you’ll want to add a spacer to bring it up to the correct height. If it’s already close to 7/16 inch, you can install the new Thetford toilet directly without any spacer.

Overall, the Thetford # TH49FR is an easy, compatible upgrade that should install smoothly and give you a clean, reliable seal for years to come.

Are you trying to see if Brinkley is going to replace it? How long have you had the camper?