We say “water under the bridge” to refer to past experiences and conflicts which we have decided to forget. This idiom compares these memories of the past to water which has passing under the bridge.

For example: “Aren’t you still angry about what she said?” Answer: “No, that was a long time ago. It’s all water under the bridge.”

You can’t quite see it here, but there is water under this bridge:

Gone, but not forgotten?

I can hear it trickling now…..

…. and don’t call me a drip.  Please.  Puhhhh-leeeeaaase.