Rough in Dimension for RV Toilet
Updated 09/28/2026 | Published 09/07/2026
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Question:
What is rough space in needed for installation?
asked by: Rod L
Helpful Expert Reply:
Thanks for letting us help Rod. The rough in measurement for the Dometic 321 Full-Timer RV Toilet is 11". This measurement is taken from the wall behind the toilet to the center of the floor flange. Unfortunately, the Dometic 321 is no longer available. After comparing the available replacements, I'd recommend the Thetford Aqua-Magic Style Plus RV Toilet # TH89SE. The # TH89SE is also a low-profile, bone colored RV toilet with a ceramic bowl, and its rough-in, height, and width dimensions are virtually identical to the Dometic 321.
There are a couple of minor differences. The Dometic 321 is approximately 1 inch deeper, so its seat has a slightly more elongated shape. The other noticeable difference is the flush pedal location. When facing the toilet, the Dometic 321 has the pedal on the right side, while the # TH89SE uses a front center flush pedal.
Are you replacing an existing RV toilet? If so, do you know the rough-in measurement of your current installation?
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Kent
9/12/2026
Works great, easy to install
Christopher H.
9/14/2026
Product Page this Question was Asked From
Thetford Aqua-Magic Style Plus RV Toilet - Low Profile - Round Bowl - Slow Close Lid - Bone Ceramic
- RV Toilet
- Low Height
- Round
- Slow Close Lid
- 11 Inch Rough-In
- Gravity Flush Toilet
- 360 Swirl - Better
- Ceramic
- Off-White
- Thetford
more information >
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Steven
9/12/2026
I recently replaced my 321 with the newer updated version which is the 421. It is less deep and looks way sleeker. It has a new flush mechanism apparently and it has a slow close lid. It looks very sleek and modern.