All that effort for nothing with

(みず)(あわ)になる, also 水の泡なる, says that work or plans have come to nothing. Like a bubble bursting, the hoped-for result disappears. English equivalents include “go up in smoke” and “go down the drain”.

Literal Meaning

This expression literally translates as “to become bubbles of water”.

Usage Notes

Use it when work that seemed likely to succeed produces nothing or is suddenly undone. The phrase expresses disappointment and frustration at the wasted effort.

Examples

All that murder planning for nothing with 水の泡になる

Learn the meaning and usage of the idiom 水の泡になる in Japanese, with examples from manga.
名探偵コナン » Volume 5 » Page 83

After discovering who the murderer is, Conan explains why the murderer went after Ran. He pinpoints when Ran unknowingly discovered a vital clue.

コナン:
「あの(とき)(らん)(こと)()にもとめてなかったが、もし(おも)()されたらせっかく()()てたこの殺人(さつじん)計画(けいかく)がすべて(みず)(あわ)になる…」
“Ran didn't think anything of it at the time, but if she remembered it, all the murderous plans he worked so hard on putting together would go up in smoke.”

Losing all that built-up friendship with 水の泡になる

Learn the meaning and usage of the idiom 水の泡になる in Japanese, with examples from manga.
一週間フレンズ。 » Volume 3 » Page 51

Although Fujimiya loses her memory of friends every Monday morning, she and Hase have become close enough that she feels comfortable around him when meeting him “for the first time” at school each Monday. Hase fears that progress will be lost during summer break.

長谷(はせ):
(おれ)はせっかくの(いま)までの努力(どりょく)(みず)(あわ)になるのが(いや)なの!」
“I hate seeing all my hard work up to now go down the drain!”
藤宮(ふじみや)さんも頑張(がんば)ってきたのに!」
“Fujimiya-san has worked so hard, too!”
桐生(きりゅう):
「あーはいはい」
“Yeah, got it.”