Can Seaflo Ceramic RV Toilet w/ Sprayer Attachment Replace Dometic 300 Series

Updated 03/18/2026 | Published 12/16/2025

Question:

Can this replace my Dometic 300 series toilet?

asked by: Luke

Expert Reply:

Hey Luke! It may be possible to replace your Dometic 300 series with the Seaflo Ceramic RV Toilet w/ Sprayer Attachment # SE42MR but you will need to measure to be sure. This toilet requires a rough-in measurement of 10" for installation. This is the distance from the wall to the center of the floor flange, see the attached photo. If you meet this requirement you will be able to install the Seaflo in your trailer.

What kind of trailer do you have?

expert reply by: Robin H

Rough-In Measurement
(click to enlarge)

Robin H.

1/19/2026

Hey Luke, did the Seaflo ceramic toilet end up fitting your trailer once you checked that 10-inch rough-in measurement? Knowing how it worked out could help others looking to replace their Dometic 300 series too.

Matt

3/17/2026

Hey Robin H, I have the same question as Luke. I have a 2016 Airstream Pendleton with a Dometic 310 installed and want to go to the elongated toilets. I know the 320 won't fit but wasn't sure about this Seaflo one. Any advice?

Robin H.

3/18/2026

@Matt that rough-in measurement is the key to fitment for pretty much any replacement toilet. If you have 10" from the wall to the center of the floor flange the # SE42MR will work in your Airstream.