hot and cold water
Refers to water in general, especially when both hot and cold water are available or used. Often appears in contexts of wastefulness or abundance.
Spend money like water.
something abundant; something plentiful
Used figuratively in the phrase 湯水のように to describe spending or using something without restraint, as if it were as abundant as water.
See also: 湯水のように使う
He spends money like water.
Compound of 湯 (hot water) and 水 (cold water). The figurative sense derives from the idea of using water freely.