Hi. I'm on the last job after plumbing my whole new bathroom in and I need some advice.
I have a leak on the waste directly under the sink. It's coming from the actual drain hole, the part that's fitted through the hole in the ceramic basin to the plug-hole. I bought the sink and taps (used) from eBay so there's no instructions, so I don't know if I have to mastic under the metal plug hole. There's a flexible white piece between the metal and the ceramic but the water is leaking out underneath it. The first sign of water is at the metal thread connected to the bottle trap. I've used PTFE tape on the metal thread of course but it's still leaking.
Thanks for any suggestions - Katrina
I wonder if I should just bung some of that clear leak sealer all around the underside of the basin hole?

Hi Katrina:

My guess is the problem is at the gasket joint under the sink (see image). Take some toilet paper and run it up around that joint... does it get wet? If so, you 'll need to disassemble the unit, reputty the flange and then add some pipe dope to the threads of the body of the pop-up assembly. Reassemble and tighten all up... should fix this.

If not the gasket, look at the picture and let me know more... O.K?

MARK