How do you explain Water Under Mat?

I have often heard it referred to as water under the bridge. I take that as to meaning that we can take it with a grain of salt. We can pay attention to it or just tuck it away and not let it bother or get under our skin. Water under the mat must be the same kind of thing. You can leave it there and let it go away on its own or take care of it when you see it there.

I'm not sure if "water under mat" is the same as "water under the bridge" or "sweep it under the mat". "Water under the bridge" refers to something that happens that we have no control over and, once it's "under the bridge" it's gone. It's something that we should just put behind us because it's over. "Sweep it under the mat" means that we should put it out of sight, like sweeping dirt under a mat. Out of sight, out of mind. It could also mean that we should keep some things hidden from others, such as something a friend tells you in private.

sounds a bit like that saying,"water under the bridge". That would mean it is done and over with and in the past. It is time to move on and forget about it.