water over the dam
Also, water under the bridge. Something that is over and done with, especially an unfortunate occurrence. For example, Last year's problems with delivery are water over the dam, or Never mind that old quarrel; that's water under the bridge. These metaphoric phrases allude to water that has flowed over a spillway or under a bridge and thus is gone forever. The first term was first recorded in 1797; the variant dates from the late 1800s.
Words nearby water over the dam
water off a duck's back,
water on the brain,
water on the knee,
water opossum,
water ouzel,
water over the dam,
water ox,
water paint,
water park,
water parting,
water pennywort