Flush with cash

What does "flush with cash" mean and what is the origin of the phrase?

Well, it means having plenty of it - that's the easy bit.

As to the origin, I am going to have to leave that to someone more expert.

DFG

On reflection, I will have a go: I am more than willing to be corrected.

One of the meanings of 'flush' is level with the surrounding surface, so if you fill a hole with something until it is 'flush' you have filled it completely, so 'flush with cash' might mean full of the stuff.

DFG