like water; as if it grows on trees
Set phrase used to describe spending money or using resources freely and without restraint, often in a critical or cautionary tone. Typically appears with verbs like 使う (spend).
See also: 湯水
He spends money like water.
You must not consume resources as if they grew on trees.
Standard kanji spelling using ごとく.
Variant using the kanji 如く; less common in modern writing but still seen.
From 湯水 (hot and cold water) + の + ごとく (like). The phrase likens spending to using water, which is traditionally seen as plentiful and free.