The Complete Guide to Identifying Your Dometic RV Toilet

As an RV owner, one of the most important fixtures in your motorhome or camper is the toilet. Having a high-quality, reliable toilet like those made by Dometic can literally make all the difference on long trips and weekends away in your home on wheels.

But with so many Dometic models and series available, how do you determine exactly which toilet you have installed? Identifying this allows you to properly maintain your toilet, order the correct replacement parts, and ensure optimal performance.

In this comprehensive guide, we’ll provide tips on how to identify your Dometic toilet model, compare the features and sizing between different models, and outline everything you need to know to keep your RV toilet in tip-top shape.

A Breakdown of Popular Dometic RV Toilet Models

Let’s start by reviewing some of Dometic’s most common toilet models found in RVs:

Dometic 300 Series

Part of Dometic’s value line of toilets, the 300 series comes in two models – the 310 and the more compact 320. Both feature:

• Elongated bowl for comfort
• Porcelain construction
• Powerful whistling flush valve
• Water saving adjustable regulator
• Available in white, bone, dune, biscuit and black

The 310 is a 10” rough-in size while the 320 is 9” rough-in.

The 310 is known for its ruggedness and durability, while the 320 offers an affordable option for tight spaces.

Dometic 400 Series

Featuring elegant styling, this residential-style toilet comes in 10”, 12” and 14” rough-in sizes. Details include:

• Contemporary, sleek bowl design
• Ultra quiet flush
• High gloss finish
• Heavy duty construction
• Elongated bowl and seat

The 400 series is at home in larger RVs where owners want a toilet similar to what they have at home.

Dometic CTB40

The CTB40 is uniquely designed for compact bathrooms with limited space. It features:

• Slide action bowl to save space
• Fits smaller RV floorplans
• Round bowl design
• Only 17.5” x 15” footprint
• Hand spray attachment option

With the minimal dimensions of the CTB40, you can have a functional toilet even in the tightest compact trailer layouts.

Dometic 530 Series

This lightweight toilet uses a one-piece design for easy cleaning. Features include:

• Single unit construction
• Foot pedal flush actuator
• Available in bone, white and bisque
• 9” rough-in size
• Good for light to medium RV usage

The streamlined 530 series toilet works well for budget-focused RV owners.

As you can see, Dometic offers a wide range of RV toilets suited for different needs. The key is identifying exactly which model you have.

Locating Your Dometic Toilet Model Number

If the model number isn’t clearly visible on your toilet, don’t worry – here are some tips for tracking it down:

Check for Labels or Stickers

Dometic products usually have stickers or metal labels with the model details. For toilets, common locations include:

• On the back of the toilet bowl near the tank
• Underneath on the base of the toilet
• On the side or bottom of the porcelain tank

An example of a label on a Dometic RV toilet

On other Dometic products like refrigerators, you may need to open the door to find the label on the interior cabinet wall.

Lookup in the Owner‘s Manual

If there’s no label on the unit, check the owner’s manual that came with your RV or toilet. The model details are usually listed on the front page or in the specifications section.

Measure Dimensions

You can get clues by carefully measuring the mounting area and tank dimensions, then comparing that to the specs listed on the Dometic website for various models. This helps narrow down the likely match.

Contact Dometic Support

As a last resort if you simply can’t locate any model details, contact Dometic support. Provide them with any measurements you were able to take, the RV make and model, toilet colors, manufacture date, etc. Their experts should be able to determine the closest match for your toilet.

Knowing the complete model number (usually 8-12 digits) comes in handy when ordering repair parts or cross-referencing any recalls.

Key Differences: Dometic 310 vs 320 Toilets

Two of Dometic’s most popular RV toilet models are the 310 and 320 series. As mentioned above, these both fall under the Dometic 300 line of toilets. Here we’ll compare the 310 and 320 models more in-depth:

Water capacity: At 5 gallons, the 310 offers plenty of water per flush. But the 320 bests it with up to 6 gallons capacity for its smaller size.

Durability: The 310 bowl is made from thicker vitreous china that stands up better to bumps and bouncing down the road. The 320 uses lighter ABS plastic.

Comfort: With its elongated bowl, the 310 provides more comfortable seating support. The 320 has a compact elongated shape with slightly less surface area.

Reliability: In surveys, Dometic 310 owners report very high satisfaction with reliability and performance, especially compared to other value RV toilets. The 320 scores well also but some owners report issues over time.

Warranty: Dometic provides a 2 year limited warranty on the 310, while the 320 only comes with a 1 year warranty. This highlights the enhanced durability expected from the 310.

Price: The 320 usually costs $75-100 less than the 310. But given the more robust construction and reliability of the 310, it’s worth the extra investment for many RVers.

Overall the 310 represents better bang for your buck. But if you need a smaller toilet on a tight budget, the 320 gets the job done.

Identifying a Dometic 300 Series Toilet

Dometic 300 series toilets have a contemporary, sleek appearance. Here’s what to look for:

Elongated bowl – Provides comfortable seating

Hidden backflush cylinder – For water efficient flushing

Bottom mounted china valve – Creates powerful rinse action

Ergonomic chrome flush lever – Looks nice and makes it ADA compliant

Available colors – White, bone, dune, biscuit and black

One or two piece design – Pick the version that fits your installation needs

Distinctive chrome lever flush

The 300 series combines aesthetics and functionality – exactly what you want in an RV toilet.

Measuring Your Toilet’s Rough-In Size

Toilets come in standard 10” and 12” rough-in sizes. This refers to the distance between the wall behind the toilet and the center of the mounting bolts on each side of the bowl.

Measuring rough-in is important to ensure you get the right replacement toilet or matching tank. Here’s how to measure it:

What You‘ll Need

• Tape measure
• Helper to hold one end of the tape measure

Directions

1. Have your helper hold one end of the tape measure at the base of the wall behind the toilet.
2. Stretch the tape straight forward to the center of the mounting holes on each side of the bowl.
3. Note the measurement – if it’s close to 10”, you likely have a 10” rough-in toilet. Around 12” indicates a 12” rough-in.
4. Compare your measurement to toilet specs when purchasing.

Getting the right rough-in ensures your new toilet or tank will mount properly on the existing floor flange and line up with the supply valve.

Measuring rough-in size from wall to mounting holes

Replacing One Dometic Toilet with Another

In many cases, you can replace an old or faulty Dometic toilet with a newer Dometic model. Here are some tips for this process:

• Choose a replacement toilet that fits the existing tank cutout and rough-in size
• Carefully detach the old toilet and cap the waste pipe temporarily
• Install the new toilet to the floor flange using an installation kit for a leak-free seal
• Ensure all plumbing connections are secure – supply valve, discharge, venting
• Replace ageing gaskets and seals during the swap to prevent any leaks
• Turn on water supply and test flush several times to check for leaks
• Apply caulk around base if needed for extra protection from leaks

If you don’t feel comfortable tackling this yourself, hire a professional RV technician. But following Dometic’s instructions carefully, most RVers can do this themselves. The key things are getting the right replacement toilet model and ensuring all seals are tight.

Upgrading to a newer Dometic toilet can refresh your RV’s bathroom and get you another decade or more of reliable service.

Dometic vs Thetford Toilets

Along with Dometic, Thetford is the other major player in the RV toilet industry. Here’s how the two brands compare:

Reliability: In surveys, both brands rate as very reliable. Dometic highlights its engineering while Thetford stresses “tried and true” designs.

Bowl styles: Dometic focuses more on a contemporary look while Thetford offers rounded or home-like bowls.

Features: Dometic touts more luxurious appointments while Aqua-Magic toilets earn praise for simplicity and durability.

You really can’t go wrong with either brand. It comes down to which specific model fits your needs and installation space best.

Troubleshooting Common Toilet Problems

Knowing your Dometic toilet model provides insight when troubleshooting issues like:

Clogs – If it’s a 300 series, the hidden backflush tube may be blocked. The problem may lie in the piston valve on a 400 series.

Leaks – Are seals and gaskets faulty, or is the leak coming from another source? Knowing your model helps pinpoint this.

Loose fit – If the toilet rocks, the mounting kit could be wrong for that model. Verify the toilet model and get the proper mounting hardware.

Flushing issues – Does the model have a macerator or gravity-based flush? This points to where the problem might be.

Of course you can always contact Dometic support for assistance. But identifying your model provides a helpful starting point for diagnosis.

Keys to Maintaining Your Dometic Toilet

To keep your Dometic toilet functioning properly for years to come:

• Follow the recommended maintenance schedule – This varies but plan on full servicing every 1-2 years minimum. Tasks include replacing gaskets, lubricating valves, inspecting mounts.
• Use Dometic cleaning products – Don’t use bleach or harsh chemicals. Their kits are designed specifically for RV toilets.
• Watch for recalls – If you have the model number handy, you can easily check for recalls and request replacement parts.
• Inspect fittings yearly – Check floor mounts, supply valve connections and discharge seals for deterioration or looseness. Tighten or replace as needed.

The small effort of proper maintenance goes a long way towards adding years of service down the road.

Different RV Toilet Flush Types

There are a few common types of flushing mechanisms used in RV toilets:

Gravity-flush – Uses gravity to siphon water from the tank into the bowl when flushed. Most affordable and simple but not as powerful.

Macerating – A blade mechanism grinds waste into smaller pieces before flushing down. Allows for smaller diameter plumbing.

Pressure-assist – Uses compressed air to forcefully jet water from the tank into the bowl. More powerful flush but uses more water.

Vacuum-assist – A vacuum pump suctions the water and waste out of the bowl instead of pushing with water. More efficient but higher cost.

Back-flush – Found on Dometic 300 models, uses a charge of water in a hidden tube to help rinse the bowl. Saves water.

Make sure to get the right replacement toilet with the flushing type designed for your RV’s plumbing system. This ensures optimal performance.

Do Toilet Tanks Have Standard Sizing?

While toilet bowls come in standard 10”, 12” and other sizes, tanks can vary more in their dimensions and connections. Here are some tips for sourcing a compatible replacement tank:

• Measure the existing tank and match the dimensions as closely as possible
• Ensure the tank has the proper fitting for the toilet’s water supply valve
• Match the outlet hole to the bowl inlet size – often 2” or 3” diameter
• Pick a tank made of similar material as existing – porcelain, plastic etc.
• Choose the correct rough-in size
• Consult with the toilet manufacturer if unsure about compatibility

Having the toilet model number again comes in very handy for determining the right replacement toilet tank.

In Closing

I hope this guide has helped shed some light on identifying your existing Dometic RV toilet. With models ranging from the 300 series to the 400 series and beyond, it’s crucial to know exactly which toilet you have before maintenance, repairs and especially replacements. Pay close attention to critical dimensions like rough-in size, take time to inspect any labels or markings on the unit, and don’t hesitate to reach out to Dometic if you need assistance identifying the model.

Knowing your toilet model helps you troubleshoot any issues that come up, secure the proper fitting replacement parts, and determine if a recall applies. Keeping this information handy ensures you can keep your RV’s bathroom facilities running smoothly for many more years of comfortable camping and exploring new destinations!