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C403L Cassette® Toilet

Cassette® toilet with removable waste water tank with no-splash pour-out spout and direct connection to the central water tank

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C403 Cassette® Toilet

  • LED level indicator can be installed on the left or the right
  • Electric push button for adding water to the bowl
  • Removable seat and cover for easy cleaning
  • Integrated automatic presure release vent
  • Removable holding tank with no-splah pour-out spout
  • Waste tank comes with wheels and retractable handle
  • Black water tank capacity: 5.1-gal
  • Flush water tank connects directly to RV central water tank

Installation Manual

Parts List

Frequently Asked Questions

Cleaning and maintenance

Clean toilet with Aqua Clean® or Aqua-Foam™. Add Toilet Seal Lubricant and antifreeze to the toilet bowl. Clean black and grey water tanks with Tank Blaster®. Add holding tank treatment, Drain Valve Lubricant, and antifreeze if freezing is possible, to each tank. Sanitize the fresh water tank with Fresh Water Tank Sanitizer.

Enzymes accelerate the natural breakdown of waste and toilet paper in the holding tank to reduce the malodors and prevent clogging during discharge.

Never leave the black tank dump valve open during use even if you have a sewer hookup at your campsite. If left open during use, the liquids will quickly drain leaving a pyramid of solids in the tank directly below the toilet. The solids are a source of odors and can plug the toilet as well as the entire tank when trying to remove the build up. You can leave the grey water tank dump valve open with a sewer hookup.

However a good rinsing and cleaning with Tank Blaster® may needed overtime to remove any grease and solids built up in the tank.

Tank Blaster®

To clean gauges, choose a warm day, above 75F, pour 1/2 of bottle of LGC into 40 gallon black holding tank through toilet opening. Pour 1/2 of bottle of LGC into 40 gallon grey holding tank through sink or shower drain. Flush the drain with running water and fill the tank. Mix by driving around and let it sit 24 hours. Drive vehicle again to loosen deposits. Empty and rinse holding tank. Product’s effectiveness doubles between 75 and 85 F. DO NOT use in freshwater tank.

Protecting the seals must be foremost in mind when cleaning the RV toilet. Bleach and acids found in most household cleaning products will potentially dry out and damage the seals. Mild organic acids and Citric Acid will not cause harm. The acids generally found in household toilet bowl cleaning products, will dull and pit the bowl surface.

“Non-abrasive” household cleaning products may still be abrasive enough to dull and scratch the RV toilet bowl making it vulnerable to future stains. Thetford® products are specifically developed and tested on RV surfaces and they’re compatible with RV plumbing systems.

Toilet treatments are important for keeping holding tanks clean free from clogging. Treatments breakdown solids, clean the walls of the tank, and reduce malodors.

The biological and enzyme ingredients in Aqua MAX® accelerate the natural breakdown of waste and toilet paper in the holding tanks to reduce the malodors. The fragrance in the product assists to mask any remaining odors.

Thetford® recommends replacing the lip seal every four to six years, depending on how often the toilet is used. Some suggest treating the seal between the bowl and Cassette® at least twice a year.

More than likely, the cause of the leak is a bad vacuum breaker and this would need to be replaced.

Aqua Clean® is a multi-use cleaner for all surfaces including your toilet. A soft cloth or a sponge is recommended. Bristle brushes are discouraged as they may mar the surface of the toilet.

Troubleshooting

The serial number label can usually be found near the location where you remove the tank. There is also a serial number on both the cassette and the tank.

For models SC and CW, you need to troubleshoot the direct connection to the RV freshwater tank.

For parts and/or service – including those under warranty – contact a local Thetford®/Norcold® Authorized Service Center (ASC) or an RV Dealer. Under the Warranty Program, Thetford®/Norcold® replaces or repairs toilets and/or parts, and pays the Authorized Dealer for warranty labor.

Warranty Information

To help identify the Thetford® toilet, please send over some pictures of the unit and/or provide answers to the questions below:

Is the unit a hand flush, foot flush, or wall panel flush?

If a hand flush:

Is it a mechanical lever or an electric button?

If it is an electric button, does it have one button or two?

If a foot flush:

Does it have one or two pedals?

Locate the pedal(s) when sitting on the toilet (left side or center).

If a wall panel flush:

Does it have one or two buttons/switches?

*Please also include a picture of your wall panel?

Is the bowl porcelain or plastic?

How to

It’s recommended not to travel with water in the flush tank to prevent water damage to the vehicle. For example, Thetford® advises against traveling with water in the flush tank of the C400 bench cassette toilet.

All Thetford® toilets are tested up to 350 lbs. / 159 kg.

Generally, there is a data tag on the back of the toilet (this can be a tight fit to get to) but can sometimes be on the base of the toilet, depending on the model.

RV Toilets Serial Number Identification

RV toilets use a small amount of water during flushing

  • Only 1 qt of water is used for flushing, opposed to 1.6 gallons used by a home toilet

Holding tank holds waste for several days – it’s not a mini septic tank

Major challenges:
  • Deodorizing the RV waste holding tank
  • Keeping the holding tank clean
  • Treating super-concentrated waste

No, a permanent toilet is not the same as a macerator toilet. A permanent toilet uses gravity to evacuate waste into the holding tanks while a macerating toilet generally have a pump with a macerator that breaks down and pushes waste into the holding tanks.