We found one dictionary that defines the word passing waters:

General (1 matching dictionary)

1. passing waters: Vocabulary.com

(Note: See passing_water as well.)

Definitions from WordNet (passing water) ▸ noun:  a euphemism for urination ▸ Also see passing_water ▸ Words similar to passing waters ▸ Usage examples for passing waters ▸ Idioms related to passing waters ▸ Wikipedia articles (New!) ▸ Words that often appear near passing waters ▸ Rhymes of passing waters ▸ Invented words related to passing waters