In my own apt, if i get up to wee in the night, I leave it. Anything else, I flush. Not because I'm afraid of waking anyone, but the noise annoys ME! which means when I have company, or am at someone else's home, I have to remember to fllush all the time! the only exception is at my mom's where I have my own loo, and no one else will be using it between the time i go to bed, and wake up. I've also never been anywhere where they've said don't flush unless its brown, so I guess I've been lucky!