Looking for a source of

'Life is like a sewer. you get out of it what you put in,'
quoted by a commenter (commentator ?) on Tom Lehrer's
Copenhagen Concert on YouTube, I got this link.
Google takes you interesting places, accidentally.
But the quotation seems to be a translation of a Danish quip-proverb:
Livet er som en kloak, Man får det ud af det, man kommer I det.

(Jo, jeg kan læse dansk.)