What does “beaucoup d’eau a coulé sous les ponts” mean in French?

French marks a long stretch of time with a river image: beaucoup d’eau a coulé sous les ponts, “a lot of water has flowed under the bridges.” It means much has changed since some past event. The version bien de l’eau a coulé is a slightly more literary way to say the same. English has “water under the bridge,” but the French one is about elapsed time, not forgiven grudges.

A Radio-Canada reporter opens with the 1976 Olympics and says that, fifty years on, bien de l’eau a coulé sous la plus haute tour inclinée au monde. He swaps ponts for the stadium’s leaning tower, a small pun that only works if you know the original. The standard idiom is the same in France and Québec, and it usually follows a date or a number of years.