Replacing Thetford Aqua-Magic Toilet with Dometic 420
Published 10/28/2026
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Question:
Can I replace my Thetford Aqua-Magic Style II Part number: 42071 with a Dometic 420?
asked by: Jared
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Expert Reply:
Thanks for letting us help Jared and thanks for including the photo. Yes, you can replace your existing Thetford Aqua-Magic RV Toilet, similar to # TH35SE, with the Dometic 420 RV Toilet # DMC67JF. We also carry the same Dometic 420 in tan with # DMC77JF if you'd prefer that color. Both toilets use the same 2 bolt mounting pattern, so the installation should be pretty straightforward without needing to modify your existing floor flange.
Another important measurement when replacing an RV toilet is the rough in distance, which is measured from the wall behind the toilet to the center of the floor flange. The # DMC67JF requires a minimum rough in of 7-5/8", while your existing Thetford requires 9-1/2". Since the Dometic requires less clearance, there will not be any issues with the toilet fitting in the available space. The one thing you may need to address is the water supply connection. The connection on the Dometic 420 may sit a little farther away from the wall than it does on your existing Thetford, so your current water supply hose may not be long enough. Both toilets use a standard 1/2" threaded water supply connection, so finding a longer hose should be simple if needed. Your existing hose may already have enough length, but it probably wouldn't hurt to have a longer one on hand before starting the installation.
Are you having issues with your Thetford or are you mainly looking to upgrade to the Dometic 420 for a more comfortable toilet?
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Product Page this Question was Asked From
Thetford Aqua-Magic Style II RV Toilet - Low Profile - Round Bowl - Slow Close Lid - White Ceramic
- RV Toilet
- Low Height
- Round
- Slow Close Lid
- 9-1/2 Inch Rough-In
- Gravity Flush Toilet
- Triple Jet - Good
- Ceramic
- White
- Thetford
more information >
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