How Many "Flushes" Can The Thetford C402C Cassette Toilet TH99UE Take Before Full?

Updated 04/23/2026 | Published 04/19/2026

Question:

how many flush can you do like 5 or 20 before it is full

asked by: Cyrus

Expert Reply:

Hi Cyrus!

With the Thetford C402C Cassette Toilet - Internal Water Supply - Electric Flush - Left Hand Access # TH99UE having a 4 gallon tank, it should get between 80-100 flushes. That said, there is no exact number I can tell you as there are a lot of variables. Like how long you hold the flush button, if you are adding water before using and then flushing, so on and so forth.

Knowing that and that the "holding" tank has a 5.1 gallon capacity, I can pretty confidently say you will get more than 5 to 20 flushes, likely around 30 to 40. I just can't give you an exact number again as there are just too many variables. Like, did you have Taco Bell earlier? I think you catch my drift on that part. There is also a very clear indicator for when the cassette is full, so no guessing on that front, which is nice.

What are you wanting to install this in?

expert reply by: Lazer S