leak vs passing water

leak and passing water both are nouns.

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

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

Other synonyms of leak include making water, wetting.

leak (noun)	passing water (noun)
unauthorized (especially deliberate) disclosure of confidential information	a euphemism for urination
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

leak (verb)	passing water (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