Water under the bridge
Meaning: Forgiven past events
Originated in: 🇬🇧 United Kingdom
Like water under the bridge
Earliest attestation: The Parliamentary Debates, Fifth Series, Volume 127 (March 1920)
This idiom comes from a metaphor of how time flows like a river. Once water flows past a bridge, it’s never flowing back upstream to revisit it. So time flows by unstopping. Once a moment passes, it is gone. It cannot be revisited, changed, or undone.
Specifically, this idiom is typically used in the positive sense of “all is forgiven”. Maybe you had a fight with a friend, but now you have made up. It would then be “water under the bridge”.
Or maybe someone clearly wronged you. However, once you forgive them, the mistake is then just water under the bridge. If you have truly forgiven someone, you will not bring the hurt up again. The past stays in the past like water stays downstream.
It can also be used if you’re talking about a past mistake someone made. You do what you can to remedy the situation and learn from it, but eventually you have to move on and leave the past in the past. Ultimately, this is a saying about forgiveness and moving on.