For vehicles with on-board water tanks, flush waster is drawn from the vehicles fresh water tank.
Thetford C223 CS Cassette Toilet
 
The built-in cassette toilet consists of two parts: a permanently installed toilet and a removable waste holding tank. A clever indicator lets you know when the tank needs to be emptied and you can access and remove the waste holding tank through a small door on the outside of the vehicle.

•Lightweight, high-quality, durable plastic
•Quiet yet powerful flushing system with full bowl coverage
•Waste holding tank indicates when it needs emptying
•Waste holding tank on wheels
•Vent button for emptying without splashing
•Automatic pressure release vent prevents gas build-up, ensures splash free tank opening
•Built-in rotating spout for emptying
 
Please note that the cassette door is not included in price