Basin waste connection (leaks)

[Frank Stacey]

Having just (about) completed installation of a new wash-hand basin none of my worries about plumbing the hot and cold water supplies were realised. However, I now find that there is a leak from the basin waste outlet. This is a metal tube with the "plug hole bit" at one end and a thread at the other. It came complete with a plastic nut. I put a bit of sealant round the plug hole bit but just tightened the big plastic nut as much as I dared. It is around this nut that the leak is occurring. What is the approved method of sealing this sort of thing? Sealant, ptfe tape and a few plastic washers are lying around ready to used. Are any of these appropriate?

TIA

Frank [ the slightly less tentative plumber]

[Set Square]

Use a large washer, with some Plumbers Mait spread on its upper surface, under (or, strictly, *above*) the nut. Why is the nut plastic? A brass one would be far better.

[BigWallop]

A ring of silicone around the flange at the plug hole end and on top and bottom of the rubber washer before putting the nut on. Make a sandwich between all the waste outlet parts and the basin. These leaks are very common when the water seeps passed the waste outlet and down around the thread. The best thing to use as sealant is gutter seal, but this is black and very messy to work with so keep a damp cloth handy to wipe everything over once you squeeze the excess out. But normal silicone works just as well.

[Adrian Berry]

The best method is a large conical rubber washer that fits over the metal waste replacing your current arrangement. It is compressed by the nut (and a supplied washer) and seals the waste in the same way as the less substantial (but similar in cross-section) rubber washer in a compression (or Universal) waste pipe fitting.

Plumbers merchants rarely seem to sell them but they are stocked by Homebase.

When I don't have one to hand, I tend to use Plumbers Mait (a non-setting mastic that comes in tubs, also useful to set the basin on the pedestal) between the lip of the grate and the basin, and a bead of decent silicone on bothe sides of the washer before doing up the nut. Some people partially tighten the nut, let the silicone cure to a beautifully fitting custom washer and then fully tighten the next day but I have never found this to be necessary.

HTH Adrian

[Pete C]

Hi,

Also some goop like Boss White and maybe a little hemp under the flange on the basin side would stop water getting to the thread and wicking down.

The other way is to use some silicone, tighten it a bit, leave it to set then tighten fully. But use a thin layer of vaseline, wax polish etc on the basin to make it easy to dismantle again.

cheers, Pete.

[Frank Stacey]

Thanks - Hombase's conical rubber bung seems to have worked a treat!

Frank