The Overflow Tube empties directly into the toilet bowl. This water raises the water level in (refills) the bowl. If it weren’t for the Refill Tube there would be only a small amount of water in the bottom of the bowl. The Refill Tube must be located above the Overflow Tube.
Does the fill tube go into the overflow tube?
The refill tube goes into the overflow tube and that water fills the bowl after each flush.
How does an internal cistern overflow work?
When the fill valve fails, and the water in the cistern fills unstoppably, the internal overflow allows the excess water to run straight down into the toilet bowl, which ensures you won’t have a flood in your house.