RV Toilet Rough-In Distance Explained (and Why It Matters Before You Buy)

One of the most common reasons RV toilet purchases get delayed—or returned—is a simple measurement problem: rough-in distance. Knowing this measurement before you shop can save time, money, and frustration.

In this guide, we’ll explain what rough-in distance means, how to measure it correctly, and how it applies to popular RV toilet models from Dometic and Thetford.

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What Is an RV Toilet Rough-In Distance?

The rough-in distance is the measurement from the wall directly behind the toilet to the center of the floor mounting bolts (floor flange).

This measurement determines:

• Whether a toilet will physically fit in your bathroom
• How close the toilet sits to the wall
• Whether the tank and bowl will clear rear obstacles

Rule of thumb:
Your RV must have at least as much clearance as the toilet’s required rough-in—more is fine, less will not work.

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Why Rough-In Is Especially Important in RVs

Unlike residential bathrooms, RV bathrooms are:

• Smaller and more space-constrained
• Often designed around very tight clearances
• Built with standardized but compact layouts

Even a difference of 1–2 inches can determine whether a toilet installs easily or not at all.

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Dometic RV Toilet Rough-In Distances  

Dometic offers a wide range of gravity-flush and macerator toilets, each designed for different space requirements.

Common Dometic Models

• Dometic 300
  Requires approximately 8½ inches of rough-in. A compact gravity toilet suitable for many mid-size RVs.

• Dometic 310
  Requires about 10 inches. Larger bowl and more residential feel than the 300.

• Dometic 320
  Requires roughly 11 inches. Best for RVs with ample bathroom depth.

• Dometic 400 Series
  Designed for tight spaces with a minimum 7⅝-inch rough-in.

• Dometic 410 Series
  Also requires 7⅝ inches, but adds a premium feel with an industry-first compact porcelain design.

• Dometic MasterFlush 7640
  A macerating toilet with flexible placement since it’s not limited to gravity-tank alignment.

• Dometic 8920 and 510+
  Larger, residential-style toilets that typically require 11 inches or more of clearance.

Quick “Will it fit?” cheat sheet 

• The Dometic 400 and 410 are designed for tight spaces — ideal for small bathroom layouts.
• The Dometic 310 and 320 are standard full-size toilets and require more clearance.
• Macerator toilets like the MasterFlush 7640 are not constrained by a fixed rough-in — they can be placed where plumbing allows.

Thetford RV Toilet Rough-In Distances  

Thetford toilets are popular because they’re reliable and widely used across RVs—but their rough-in distances vary by model, so it’s important not to assume they’re all the same.

Thetford rough-in by model

• Aqua-Magic VI: 7-5/8" rough-in
  A great option for tight bathrooms where every inch matters.

• Aqua-Magic Style II / Style Plus / Residence: 9.5" rough-in
  These models are common upgrades and replacements, but they need a bit more rear clearance than ultra-compact toilets.

• Bravura: 11" rough-in
  A larger, more residential-feeling toilet that typically requires more bathroom depth.

Why this matters

If your RV bathroom measures:

• Under 8" rough-in → Aqua-Magic VI is the safe bet
• Around 9.5" → Style II / Style Plus / Residence fit well
• 11" or more → Bravura becomes an option

Thetford Tecma Electric Toilets

Tecma models—including:

• Nano
• Compass
• Silence Plus

use macerator technology, which means they are not restricted by gravity-tank placement. Rear clearance is more flexible, making them ideal when space is limited or plumbing needs to be rerouted.

Quick “Will it fit?” cheat sheet 

• Tight bathrooms: Thetford Aqua-Magic VI (7-5/8")
• Mid-clearance bathrooms: Thetford Style II / Style Plus / Residence (9.5")
• Roomier bathrooms: Thetford Bravura (11")

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How to Measure Your RV Toilet Rough-In (Correctly)

1. Measure from the finished wall behind the toilet (not trim or molding)
2. Measure straight to the center of the floor mounting bolts
3. Record this measurement in inches

✔ If your measurement is equal to or greater than the toilet’s requirement, it will fit.

A Pro Tip Before You Replace Your Toilet

If your RV currently has a Thetford Aqua-Magic Style II, you’re in luck—many Thetford gravity models and Dometic 400/410 toilets are designed to fit the same rough-in with no layout changes.

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Final Thoughts

Rough-in distance is a small measurement that makes a big difference. By taking a few minutes to measure before you shop, you ensure:

• Easier installation
• Better bathroom fit
• Fewer returns
• A more comfortable RV experience

Choosing the right RV toilet starts with knowing your space—and now you do.