passing water vs leak

passing water and leak both are nouns.

Word	Noun	Adjective	Verb	Adverb
passing water	Yes	No	No	No
leak	Yes	No	Yes	No

As nouns, passing water and leak are synonyms defined as:

Other synonyms of passing water include making water, wetting.

passing water (noun)	leak (noun)
a euphemism for urination	unauthorized (especially deliberate) disclosure of confidential information
	the discharge of a fluid from some container
	an accidental hole that allows something (fluid or light etc.) to enter or escape
	a euphemism for urination
	soft watery rot in fruits and vegetables caused by fungi

passing water (verb)	leak (verb)
	have an opening that allows light or substances to enter or go out
	enter or escape as through a hole or crack or fissure
	tell anonymously
	be leaked