Flush

[English4everyone]

Which would you use on a sign?
A. Flush after leaving the toilet.
B. Flush up after leaving the toilet.
C. Flush out after leaving the toilet.
D. Flush / Flush up / Flush out.

[JohnParis]

I would use none of the phrases you have provided.

Rather, on a sign I would write the instructions "Please flush the toilet after use."

You would have to have very long arms to flush a toilet after you left it .