Slotted waste bathroom sink

[gaffnr]

Hi All, probably really daft this but any help appreciated.
Im trying to install a bathroom sink with a built in overflow within the ceramics. Ive bought a slotted waste from a mail order company as i thought this was needed for any overflow water to make it into my waste pipe. I was surprised to receive it and find it had two slots in it. The one that was aligned to the overflow is fine but wouldnt the other slot allow waste water coming down the plug hole to leak out.

 

[seco services]

yes this waste is ok for your basin. stick it in it will work fine.

 

[TicklyT]

That is the right waste, and it probably will leak. It's a design fault common to nearly all basin wastes made since Victoria was on the throne.

It doesn't matter if there is one slot, two slots, or a hundred slots. The problem will still be there.

There is no seal to stop water running around the thread. See ChrisR's sketch, FAQ no. 26 //www.diynot.com/forums/viewtopic.php?p=772251#772251

Fit a Basin Mate washer, or use sealant around the thread when you fit the back nut.