The overflow drain on my bathtub leaks behind the wall when water goes unto the overflow drain. From the underside (acess door in the ceiling downstairs) it appears the water is leaking from around the gasket, possibly from an inproper seal. My facility maintenance person seems to thing its not supposed to be for overflowing water but for more of an air vent. My question is, if the drain was sealed properly, would it be leaking even if the water was overflowing through the drain?

Hi Bud

Ahhh... maintenace dude that has no clue how tub drains work or are assembled... *UGH*

The tub waste and overflow assembly of a tub is designed to be 100% leak-proof. The overflow does not act to introduce air into the system... it is designed to catch any water that may get above the overflow... acts as a defense against the tub overflowing.

Air is introduced into the tub drain system itself via a tub vent that is somewhere beind the wal so you can't see it.

Now, the maintenance person should be able to get a basic replacement tapered overflow gasket (see image) and install it through an access panel upstairs or can replace it through the front of the tub by removing the face plate and exchanging old for new, OK? Should be that simple!

Mark