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Leaking raising main coming out drain pipe! (Read 5056 times)
Drewyd
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Leaking raising main coming out drain pipe!
Feb 18th, 2013, 6:08pm
 
Hi all,

I have a concrete floored wet room - the rising main comes though the outer wall (2 foot thick random stone) and must tee somewhere as it then comes up through the floor in two places, under the sink and under the loo cistern. The cistern pipe continues up into the attic to feet the rest of the house.

I noticed a few days a go the sound of a running tap - but no tap is running. The ballcock on the cistern is not running either. When I listen with a stethoscope the sound is loudest on the cold feed pipe under the sink.

Looking outside, the drain from the floor under the shower & the sink drain exit as one pipe through the wall and there is significant flow of clean water coming out constantly. Turn off the main top cock to the house - the drain flow stops after a few seconds. Approx flow rate 1 litre/min. There must be a leak under the floor of the wet room somehow getting into the drain? Assume there is a T on the drain from shower & sink, and a T also on the main cold water - but it seems to stretch the imagination that a leaking feed T and a leaking drain T should be flowing well - one into the other? There are no internal signs of a leak- damp patches etc.

Son suggested an overflow, but there is none apart from the cistern which flows into the pan anyway. Boiler is external to the house, so if a cold leak was there, it could not be coming out the drain in question.

Any ideas? Don't want to dig up the wet room floor in the hope of finding it, but it can only get worse. BTW definitely not flowing like this in the autumn - it is recent over winter.
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scotspark
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Re: Leaking raising main coming out drain pipe!
Reply #1 - Feb 18th, 2013, 11:31pm
 
you sure its not cistern overflowing into waste?
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thescruff
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Re: Leaking raising main coming out drain pipe!
Reply #2 - Feb 19th, 2013, 1:21am
 
Could be the incoming mains outside the property.

You should be able to test that by turning the inside stopcock off.
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Drewyd
Re: Leaking raising main coming out drain pipe!
Reply #3 - Feb 19th, 2013, 8:52am
 
scotspark wrote on Feb 18th, 2013, 11:31pm:
you sure its not cistern overflowing into waste?


Yes, it can't be that for two reasons - the ballcock in the cistern is not flowing constantly & the overflow goes into the bowl and down the sewer pipe - not the drain that is flowing... but thanks for the suggestion!
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Drewyd
Re: Leaking raising main coming out drain pipe!
Reply #4 - Feb 19th, 2013, 8:57am
 
thescruff wrote on Feb 19th, 2013, 1:21am:
Could be the incoming mains outside the property.

You should be able to test that by turning the inside stopcock off.


Great idea, but sadly there is no inside stopcock, the only one is underground outside (about 2 feet from the house wall hidden under a breeze block).

The house is 300 years old & only got running water in the 70's, you would have thought it would have been better specc'd - but it's what I have to live with! I live on a remote Scottish island - everything here is rustic to say the least!

Cheers,

Andy
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thescruff
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Re: Leaking raising main coming out drain pipe!
Reply #5 - Feb 19th, 2013, 9:15am
 
You may have to dig an exploritory hole or two.

Does the noise stop when you turn the stopcock outside the wall off
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Drewyd
Re: Leaking raising main coming out drain pipe!
Reply #6 - Feb 19th, 2013, 9:37am
 
thescruff wrote on Feb 19th, 2013, 9:15am:
You may have to dig an exploritory hole or two.

Does the noise stop when you turn the stopcock outside the wall off


Yes it does - and the flow from the waste stops too after a few seconds.
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Re: Leaking raising main coming out drain pipe!
Reply #7 - Feb 19th, 2013, 10:15am
 
I assume the cold water feed is copper, I'm also assuming it was buried in concrete without adequate protection. It's very common for pipes buried in concrete to corrode away and leak like a sieve usually into the ground beneath.

I'm thinking perhaps the mains and waste pipe run together in the same trench or very close to each other and the water is flowing into a weak spot in the waste. If the waste is plastic solvent weld the only weak spot should be beneath the shower, if the pipe was fitted together properly. Unfortunately this does not help much as you have no idea where abouts the mains pipe is leaking anyway.

If you don't want to dig up the whole floor, my advice would be to dig a small hole where the mains enters the building and cap of the cold feed to the bathroom then T off again above the floor and run surface pipe to the shower and basin. You don't mention where the hot pipes are, if they are in the same place they will most likely fail too, eventually.
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Re: Leaking raising main coming out drain pipe!
Reply #8 - Feb 19th, 2013, 1:34pm
 
I would dig between the stopcock and the wall first to see what you find without too much damage.
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Drewyd
Re: Leaking raising main coming out drain pipe!
Reply #9 - Mar 2nd, 2013, 8:03pm
 
thescruff wrote on Feb 19th, 2013, 1:34pm:
I would dig between the stopcock and the wall first to see what you find without too much damage.


This is just what I did, thanks. The alkathene mains pipe was terminated (buried about 6" down in soil) with a brass union, going to what seemed to be 22mm copper - then disappearing through  the house wall with no sleeving etc.

I broke this down and made up a 22mm tail, reducing to 15mm and going through a new hole in the house wall above soil level - sleeved in a brass tube and now lagged. However my new tail would not fit into the brass union which I guess must be 3/4" NOT 22mm. Anyway, as there is no plumbers depot on the island I carefully ground out the inside of the union till my new pipe would fit.

Inside I fitted a compression  tee and ran new pipe to the loo and sink, capping off the old 15mm feed pipes where they came up through the floor. Turned it all on - job done! (no leaks!)

Thanks for all your advice - now have a leak free house...

Cheers,

Andy
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