Stopping by a brook and observing water bubbles forming and disappearing, a Japanese may associate those bubbles with the transient nature of life. Used poetically to acknowledge that a great effort was in vain and now has vanished like bubbles on the water.
(Style: spoken/casual/A=female, B=male)
A: Michio-kun no sakkaa ne, are dake doryokushite shiai ni sonoeta noni, toojitsu ame de chuushi ni natta n da tte.
B: Sankagetsu no doryoku mo mizu no owa ka. Kowaisooni na.
A: This thing about Michio’s soccer. He practiced so hard, but the game got cancelled because of rain.
B: Three months’ effort was all in vain! Poor thing.