I've tried the Brow Set and the eyebrow pencil. Neither is water proof or resistant. I can't imagince that their brow powder would be either, it is powder after all. That just leaves the Brow Stick (a wax formula), so maybe it is...I doubt it though.
If you need them to be waterproof I agree with what someone else said, you could add a coat of a clear waterproof mascara on top. UD makes one.