How to tell which joint a leak is coming from?

The nest of plastic piping under our kitchen sink has developed an as yet small leak. It's a combination of the main sink drain, half sink drain and dishwasher drain.
What's the best way I can tell which of the many joints is leaking? There's only dampness around the fittings at the moment so I can't actually see anything dripping from anywhere.
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Gary wrote:

Just dry everything off thoroughly with kitchen paper and monitor all joints thoroughly and regularly until you find which one gets damp first.
David
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On Thu, 27 Dec 2007 10:40:03 +0000, Lobster wrote:

The look to see if something ABOVE it is making it wet which you had not spotted earlier.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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Colour the water with a food dye
--
Alan
news2006 amac f2s com
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Alan wrote:

Now that idea I like. Might make the subsequent fixing a bit messy though unless it's all flushed through!
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Wrap a bit of kitchen roll around the joints then run water through the various fittings and see which bits of paper get wet first.
--
Frank Erskine

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Redo every joint again.
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I would agree. We came back from a walk on Boxing day to find our kitchen flooded. One of the pipes had fallen out and the dishwasher had emptied itself over the cupboard and the floor. I would also advise people to check these pipes occasionaly as they can clearly work loose.....you only need to look at a pub urinal or sink to see how unreliable they are!
If somone can recommend a particular brand that is more reliable or foolproof I would be interested to hear about it.
Tim
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In article

The best way is to use Terrain where possible - this uses solvent weld connections and won't leak ever if properly done. And just use push fit or compression etc where essential. Obviously Terrain requires more care and skill to fit - it has to be properly lined up when cementing together as you don't get a second chance.
--
*Ah, I see the f**k-up fairy has visited us again

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Gary wrote:

Dry everything with kitchen paper & use a very bright LED torch - the light makes water droplets sparkle & they are easy to spot.
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
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The Medway Handyman wrote:

Once the pipes have been dried off as above, tie strips of kitchen paper near each joint and see which ones get wet. This will locate the slowest of leaks even if is so slow that the paper dries but telltale stains will show.
Bob
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Tying little bows of loo paper round the pipes helps. See which one gets wet first.
--
"Be thankful that you have a life, and forsake your vain
and presumptuous desire for a second one."
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Gary wrote:

Find some self coloured absorbent paper and use that. I use blue, as it shows up quite well when it gets wetted. Kim wipe is one form of it and can usually be found outside a supermarket for drying the trolley handles.
Dave
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You'll probably have to dismantle the lot even if you do find which one is leaking so just bite the bullet and do that anyway. A good time to neaten it all up if it was a peacemeal development. ;-)
--
*(on a baby-size shirt) "Party -- my crib -- two a.m

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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