Condensation or leak on main cold water pipe

[Jez974]

Hi,

I am trying to determine whether we have a very minor leak in the cold water pipe or just condenation:

Situation

The mains pipe in question runs from the stopcock in garage to kitchen sink - about 5 meters in lenght. The cold water pipe directly under the sink is exposed, the rest is buried in concrete. The rest of the pipe between garge and kitchen sink is under concrete and seems to be lagged ok.

Problem

When the water in the house is not used i.e. over night, the pipe drys up. When we are out of the house and the heating is off the pipe drys up. However once we are in the house and using wtaer the pipe very quickly becomes wet again around its surface.

The pipes around the stopcock in garage are mostly dry, some very small drips only from the stopcock. The garage pipes are not well insulated, but do have some lagging.

I have verified that there isnt a leak between the outside mains and stopcock, by turning off the stopcock and checking the meter doesnt move. This is all ok.

Grateful for your views on whether we are likley to have a leak elsewhere and how to get this checked?

Many thanks
Jez

 

[wheeto]

The fact that the pipe dries up when cold water isn't being drawn through strongly suggests that it's just condensation. If anything, a leak would be worse at night when the mains water pressure rises as demand drops.

T

 

[hydrotherm]

Definitely sounds like condensation.Only way to make sure would be a pressure test on that section of pipe.

 

[justlead1]

Check out ways of reducing the humidity, Are there damp/wet things stored near the problem? often a bit of venterlation will do the trick.

 

[GQuigley67]

best cure for condensation is ventilation is your water very cold ? once there is a certain temperature difference between the temperature in the room and the temperature of the water in the pipe and if the humidity is at a certain percentage, condensation will occur this is called the "dew point temperature" when condensation will occur. With people in the house and heating on etc the humidity levels rise and condensation will occur it seems like a leak but it isn't I had the same problem at a customers house last week, you can lag it or put some sort of ventilation in the kitchen.

 

[WaterTight]

Water sitting in exposed pipe in room is under pressure to warm up by surrounding temp. Fresh water being drawn through pipe when in use is much colder - more of a contrast to surroudning temp therefore - condensation. If the pipe is wet all around the pipe and all along the pipe rather than a stream or dribble it's almost certainly condensation. Tie a couple of bits of rag within a short distance of each other round the pipe, nice and tight. And dry the bit in the middle. If it gets wet again along with the rest it's condensation.