On Sep 28, 4:43*pm, Phisherman wrote:
On Mon, 28 Sep 2009 15:44:00 -0500, Alfred K. wrote:
Consider an extreme situation: a fully opened faucet and a completely
closed pop-up bathroom sink drain. Should a properly installed overflow
opening actually prevent the sink overflowing? Or it is supposed to
just help the main [open] drain by lowering the about to overflow water
level down faster?

I would NOT expect the overflow to keep up with a fully opened faucet.
Certainly not a good idea to run a faucet full blast and leave the
room.

In the old days, a fully open sink faucet could overwhelm the sink
overflow (I did the experiment in more than one sink)

but with the mandate for "low flow" faucets I'm guessing that
overflows might now handle the flow.

cheers
Bob