A Bosh boiler 'Greenstar Ri' was installed on the wall in our kitchen a
couple of years ago. Just below the boiler in a deep cupboard-corner (that
we hardly ever look into ). This plastic pipe runs into the drain pipe from
the kitchen sink.

Yesterday we discovered that a saucepan in the cupboard that was directly
under this plastic pipe had completely filled up with water.

See this photo on picture hosting site:

http://tinypic.com/r/35at9g5/6


Checking carefully from when the boiler was on from yesterday evening to a
couple of hours into this morning, a teaspoon of water has dripped off it.

We have 'not' noticed this happening before, so we are not sure whether this
might be a recent thing happening due to the snowy weather that we have had
here in North London ?

The water seems to be dripping off the joint nearest to the camera in this
photograph.

I'm guessing there is no pressure in this pipe. So is there a glue I could
buy that I could just wipe around the joint to again seal it successfully?
Or even some kind of sealing tape that would suffice?