Italian translation needed

Factual Questions
1

Though my question is not quite as literal as the thread title suggests, I believe it has a definite answer, so I’m putting it here in GQ.

My husband is writing a play, and he wants one of his characters to say to another the Italian equivalent of the metaphoric phrase, “That’s water under the bridge.” He doesn’t need a literal translation of that phrase, unless that exact phrase is commonly used in Italian. What he needs is any idiomatic or metaphoric phrase that expresses the same sentiment, and is commonly used.

If it is germane, the characters are second generation Italian-Americans.

2

A few alternatives:

E’ acqua passata! Lit. “It’s water that passed!”

Ne e’ passata, di acqua sotto i ponti! Lit. “So much water passed under the bridges!”, a not uncommon, more faithful rendition.

E’ una storia vecchia! Lit. “It’s an old story!”

You could also opt for going Eeeeeeeeeeeeeeh! while making a dismissive movement with your hand, as if throwing the old memory behind your back.

3

Thank you. It is interesting to know that a similar expression exists in Italian. I’m sure Mr. Cee will find that helpful.