Detected small leak in new pipework - need a genius plumber!

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Hi

We have had all new pipework put in our house, plumbed in and working
for the first time this month. This included a new water mains connection for our house (about 3 bar pressure) including a water meter in the street, a new blue service pipe to the house and all water and CH pipes inside the house.

Now I have noticed a small leak as I see that the water meter is registering a usage of 3 thousandths of a cubic metre each day even though everything in the house is OFF. All taps and the loo etc have little
screwdriver operated valves just before them and all these are
turned off. The cold water supply to the condensing combi-boiler is
also turned off. So, we seem to have a tiny water leak somewhere.
It is not in the boiler I am sure since the pressure gauge stays constant
at 2 bar (middle position of gauge.) The CH system has been pressure
tested and this is fine I am told.

Finally, I have shut off the indoor stop cock and now the water meter
registers only half a thousandth of a cubic metre per day. If I turn
the indoor stop cock on again, it's back to registering 3 thousandths
of a cubic meter per day. So we seem to have a very tiny leak outside
the house and a tiny leak inside the house, somewhere.

I have been monitoring the water meter for about 10 days now and
the leak is constant.

So, we had the plumber back out and he redid some pressure tests,
testing the hot and the cold pipework at 8 bar for almost 2 hours and
he said his pressure tester (a bucket and dial???) showed no drop over
this period. So he cannot find a leak this way, but the water meter in
the street shows there is a continuous leak! Is the plumber's pressure
tester sensitive enough or do we need to try another test perhaps?

I can see no obvious leaks in our house but then again, most of our pipework is under the screed floor in the bathroom and kitchen.

Can anyone offer any advice here? Will this small leak get worse?
Could we just live with it or will it make our house damp? Such a
leak would cost us only about 1 pound per year in water meterage
charges, but that isn't the point.

We need to find these leaks but I cannot see where to start and I don't
want to dig up all the screed floor - we were just about to lay floor
tiles and move back in you see. How can we find such tiny leaks?

Any advice or suggestions or other people's experiences on such matters
would be very much appreciated.

Thanks in advance.
 
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Did you think about asking the waterboard what the accuracy of the meter is.
 
test bucket is a very good way of testing the pipework, at 8 bar you would know if you had a leak.

however certain things like the boiler would have to be isolated, as would all the rads and would not be included in the test.

Is the filler loop to the boiler disconnected
 
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You shouldn't need to dig up the floor to locate the leak if the problem is on the ground floor.

All water pipes laid into a screed are either within a duct (with a removable lid) or a plastic pipe within a larger sleeve. :eek:
 
the tiny amount of water might be explained by expansion of the pipework during the day. At night it will cool down, the meter probably only registers flow in one direction and there will probably be a check valve in the pipwork if it's a new installation.
 
3 thousandths of a cubic metre is 3 litres, not a "tiny" amount in my view. This is 2 big buckets full a week, it will make something damp. You don't have one of these push button toilet flushes do you? They are notorious for leaking at a rate that will be very hard to notice, similarly if you have the overflow piped into the pan.
 
oilman said:
3 thousandths of a cubic metre is 3 litres, not a "tiny" amount in my view. This is 2 big buckets full a week, it will make something damp. You don't have one of these push button toilet flushes do you? They are notorious for leaking at a rate that will be very hard to notice, similarly if you have the overflow piped into the pan.

Yes, 3 litres is not insignificant I agree.
As I said, all pipes are turned off at the device, the valve just before
the normal loo is turned OFF with a flat head screwdriver.
The filler loop is not connected at the combi-boiler either.

(Yes 1 thousandth of a cubic metre is 1000 cubic centimetres which is
a cubic decimetre which is 10cm x 10cm x 10cm which is 1 litre.)

I like the suggestion of the pipework expanding and the one way valve,
this definitely fits in with my observations, but 3 LITRES seems rather a
lot of expansion, does it not? Also, 3 litres per day is about 99 pence
per annum in water charges - so the water company must be making
a mint! ;)

Anyway, how can the water meter contradict the results of the 8 bar
pressure test? Should we redo the test at 8 bar for a 48 hour period
for example?? Or at 2 bar perhaps, to mimick the real conditions???

I am still stymied.

Any further advice?
 

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