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Mains water blockage.


Russell griffiths

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ok two questions here about two different supplies we have.  

 

If a mains pipe has low pressure and we have had a pressure check done by the water company is there a way of finding a blockage or break. 

I know if this was drainage we could stick a camera down and have a look, does anything like this exist for a water main it's 20mm pipe and for the life of me can't see it being possible, but I'm always amazed by new technology. 

 

Ground penetration radar? 

Am I being crazy. 

 

 

On a differant pipe we believe we have a leak, what methods are there of finding the leak, this pipe is 400m long and starts of in 50mm and drops to 32mm and then supplies to buildings outside taps are run in 20mm, I have started to dig up any stopcock I can find and check for leaks or renew them as needed so far it has made no difference, so we are thinking the leak could be anywhere on the remaining pipe. 

 

Somebody told me of gas detectors where they disconnect the water coming in and connect a coloured gas and go looking for it coming out of the ground. 

Anybody heard of this. 

Cheers. 

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If you have numerous stopcocks how about turning one off at a time and then seeing if the leak persists, assuming you have a meter and can check. If you manage to stop the leak at least you know which run of pipe is causing the problem.

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Spot on @RichS this is what I have done for the last couple of weeks changed a stoptap in the 32mm and dug up and located a couple of others, leak seems to be in the longest run, isolated all short sections and the metre is still spinning. So now we need to go hunting. 

Just looked up gas detectors and it seems that they do indeed inject a gas into the pipe work as it is easier to hear on an ultrasonic detector. 

 

 

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The water company guys still just use a listening rod to find leaks.  I watched them doing it back in the summer, trying to find a persistent leak that's been breaking up the surface of a lane near us.  It looked to me like a bit of steel bar around 10mm in diameter, with a rubber cup on the top that they placed on their ear, like a stethoscope.  It seemed to work, as after ten minutes or so of the bloke walking along, stopping every foot of so and placing the rod on the ground and listening, he marked where to dig and sure enough, they found the broken pipe right away, about 3ft down.

 

I've just done a quick web search and come up with this: http://vernonmorris.co.uk/shop/category/leak-detection/listening-sticks

 

 

 

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We have had numerous lads out from Thames water with the metal probing rods, and they can't find a thing. 

 

The thing that baffles me is they want to conserve water and stop leaking pipes but as soon as it's on private property they don't care and even told me it's down to me to find the leak as it's not there responsibility. So I offered to pay and was told they don't even supply this service I need a private contractor. 

 

This worled just baffles me sometimes. 

 

Looking up up things on YouTube I'm going to try to make one, just ordered a stethoscope of e bay. 

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If you have already found the reducer 50-32 and it is not leaking then you can Binary chop from there - assuming the pipe is reversely crushable IE plastic. ! You just go halfway along the pipe, dig a small hole around it and crush the pipe if the leak stops you can be sure the leak is in the remaining half. So you go halfway along that length and do the same - going backwards halfway if the leak persists until you are within a few meters if you think about it its only 8 holes (200, 100, 50, 25, 12, 6, 3, 1.5) and you will be sure you are very close. You can use the same approach to find the reducer if you have not already as this is the most likely point of failure. You will need a device that can crush the pipe - a fine thread G clamp of robust construction and a long Tommy bar has done it in the past for me but not on 50mm pipe!

 

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24 minutes ago, Russell griffiths said:

Just seems like a game of needle in a haystack. 

No because you have no way of knowing which half the needle is in with the haystack example. If you did the binary chop would be the fastest way to find it.

26 minutes ago, Russell griffiths said:

Going to make my listening device and keep hunting. 

Yes - provided there is enough flow it should work.

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5 hours ago, PeterW said:

Any reason for 50mm..? 32mm is fine for long runs. 

 

400m @PeterW

it reduces to 32mm at about the 200m point this is where I located a stopcock so I can isolate the last 200m to see where the leak is, 

guess what, it's in the first 200m in the 50mm. Lovely jubbly, as if I haven't got enough things to spend money on. 

Edited by Russell griffiths
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32 minutes ago, PeterW said:

So why not drop the rest to 32mm ..?? If you’ve got to dig it out, just dig and replace ..?

Ooh er. Not sure I would be happy dropping to 32mm this pipe feeds our hopefully new dwelling plus two holiday lets plus outside toilet block. 

Would be scared of lack of flow over that distance. 

Someone must have thought it necessary to run it in 50mm as it was here before we moved in. 

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4 hours ago, Russell griffiths said:

Hmn. That got me ?. It would be nice if they made a (y) type join   

 They do .... it’s called a 50mm tee followed by a 50/32 elbow ..!

 

At that size the pressure loss would be negligible. 

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