Intermittent leak from monobloc tap

[wingreen]

This one is very strange. I installed a monobloc, single lever chrome tap about 2 weeks ago. Tested before fitting and everything sound, no leaks. Then installed it into the basin - again, everything fine, no leaks. The strange thing is that, every now and again (say every 2 days or so) it starts to drip from underneath the tap (through the hole in the basin). Then it stops! I've never been able to get there when its actually dripping but clearly quite a bit comes out (as shown by the pool of water underneath!). I can see "wetness" at the base of the tap when I look up through the basin hole, but can't work out from where.
The bathroom isn't used very often (its OK, we do have another!) but I'm totally perplexed.....what on earth can cause a tap to drip/leak from underneath only now and again, that can start when its not being used, then stop by itself?! Aaaargh! Any thoughts would be very welcome

 

[Whitespirit66]

If you have isolating valves fitted, turn these off, and leave for a few days. If dry, then it's not coming from the tap connections or the tap itself.

Maybe it's coming from water spashed on the tap or basin during use. Did you put the rubber ring between bottom of tap and basin? Is the tap tight? Is the tap off-centre in it's hole, leaving a slight gap that water can get down to underneath?

 

[HERTS P&D]

It's leaking from where the 'tails' go into the body of the tap.

(thats what my crystal ball tells me. )

Andy

 

[wingreen]

If you have isolating valves fitted, turn these off, and leave for a few days. If dry, then it's not coming from the tap connections or the tap itself.

Maybe it's coming from water spashed on the tap or basin during use. Did you put the rubber ring between bottom of tap and basin? Is the tap tight? Is the tap off-centre in it's hole, leaving a slight gap that water can get down to underneath?

I fitted isolation valves but its definitely not coming from those.
I did fit the rubber ring (although it was tricky, but I'm pretty sure I got it in the right place (groove in tap).
I can see that the water splashing could be the problem - but the basin was last used yesterday evening and there were definitely no drips/leaks until sometime this afternoon (I've been keeping my eye on things a little - it must have happened in a 2 or 3 hour time gap this afternoon - not sure if it was a steady drip for 2 hours or so, or a real trickle that lasted about 10 minutes)
Its spooky!

 

[wingreen]

Finally caught it while it was happening. Quite a trickle, coming out from the base of the tap - difficult to see for sure exactly where (I can only twist my neck so much!). The interesting thing is that I tried just turning the hot water valve off - no effect, still trickling. So I turned the hot back on and turned the cold water valve off - again, no effect!
Now, some might say that both the hot and cold are leaking where they enter the tap - but whichever way I look at it, the trickle comes from one place, not two - and doesn't change when I try hot or cold on their own. Also, the tap (flexible pipe connection) is "holding water" fine most of the time...no drips/leaks to be seen from where these enter the tap.
Seems to me that the only explanation is that, somewhere inside the tap (where hot and cold "mix"" before coming out) there is a small leak. This keeps going until it "fills" some internal part and then overflows and comes out of the bottom.
Does that sound like the only reasonable explanation? (If so, will assume its a faulty tap and try and get it exchanged - though I'm not looking forward to trying to fit another one in again!)

 

[wingreen]

I've discovered that everything is fine UNTIL I turn off and on the basin that's in another bathroom which is next door to the bathroom with the problem. If I do that, in sets the trickle off.
I'm assuming that what is happening is that when I turn tap(s) back off in adjoining bathroom, then there is a short build up of "back pressure" - and this is enough to "breach" the internal seal and start the trickle (well, its more of a stream!). This trickle then continues until I shut BOTH valves off, then, when I open them again, everything is fine....until I turn taps in the next bathroom on and then off - which sets it off again.

I think that clearly suggests a weak seal inside the monobloc tap?

Any thoughts?

 

[wingreen]

I think it was a "weak" internal seal in the monobloc but I got no joy from the supplier. Water pressure is high so I've closed the stop cock a bit (I know, that doesn't change the pressure, but it does reduce the flow). That seems to have done the trick (and the reduced flow hasn't affected anything else in the house). Not ideal, I know (and I have put a note by the stop cock to make sure its always returned to sanme position if moved in the future!). I could fit a pressure reducing thingy - but, given the way my stop cock is installed (and the pipe runs that come from it), that would be a big job.
Anyway, thought I'd report - just in case someone else has similar problem

 

[melkor12]

I have a similar problem but the leak appears to be coming from the connecting studs that hold the tap to the basin.

Initially I assumed the leak was from the 10mm flexi tails but reassembling them (after checking for damaged o-rings) I ruled this out.

But I could be mistaken?

The leak occurs after I turn the taps off leaving puddles on the vanity unit inner shelf.

Grateful for your thoughts.

BTW lashing of silicone sealant has not helped

 

[Charnwood]

appears to be coming from the connecting studs that hold the tap to the basin.

It is feasible that the stud holes have been drilled into the waterway.

The leak occurs after I turn the taps off

Turning the taps on may be reducing the pressure on the holes, therefore temporarily stopping the leak.

 

[melkor12]

Hmmm, thanks for that thought.

Before I rush out and by a new momobloc tap, is it feasable to disconnect the connecting studs and repack the threaded hole with sealant before re-inserting the studs

Just an

Thanks for your help.

 

[Charnwood]

You could try wrapping PTFE tape or Loctite 55 around the studs.