How do i fix this leaking pipe?

Question

hi, just wondering how do I fix this issue. Plumbers have been out and said it’s fine. 
it seems to be possibly leaking from the black part and then drips down.

MitchellMc · Accepted Answer

Welcome to the Bunnings Workshop community @tahlia1. It's wonderful to have you join us, and many thanks for your question about repairing a leaking trap.

That's a bit disappointing that they could not locate the leak.

To pinpoint the cause you need to look very carefully as to where the first point of wet plumbing is. Take a look at the image below. If the black threads are wet, which I've circled in red, it indicates the seal for the sink waste is leaking. The sink waste needs to be removed and the black rubber seal replaced. The seal typically sits on the inside of the bowl under the waste outlet.

If the black threads are dry and the water is coming out of the area I've marked in green, it indicates there's a leak between the black waste and the white trap, which needs to be resealed with Plumber's tape.

Please let me know if you have any questions.

Mitchell