If it's yellow, let it mellow. (If it's brown, flush it down.)

If it's yellow, let it mellow. (If it's brown, flush it down.)

If there is only urine in the toilet, do not flush it. (But if there is feces in it, then do flush.) A common mnemonic used as a way to reduce water usage in places with indoor plumbing. We have a pretty restricted water supply out here, so always remember—if it's yellow, let it mellow. If it's brown, flush it down. Due to the drought, households and businesses around the state are being encouraged to adopt an "if it's yellow, let it mellow" policy.
See also: flush, if, let
Farlex Dictionary of Idioms.
See also:
  • mellow
  • Please Excuse My Dear Aunt Sally
  • flush away
  • Flushing
  • PEMDAS
  • all students take calculus
  • student
  • ROYGBIV
  • Battle Ends And Down Goes Charles' Father
  • Charles