Water leaks when mains switched on and off ?

[MRH2]

Is it likely there could be a leak in a join /copper pipe work that only really occurs when water is either flowing through or when it is initially filled/pressurised - as opposed to statically sitting in the pipe under mains pressure?

The actual scenario is the mains was switched on and off multiple times there was a leak but have since been unable to duplicate.

Thanks!

 

[dancinplumba]

Hi, need to think awhile and digest this.........Yes, until all the water as leaked out.

 

[rpm]

Anything is possible. Expansion & contraction can do things.

 

[Chuck]

What was the humidity on the day the 'leak' occurred? Is it possible that the flowing water cooled the pipe to below the dew point so what was noticed was actually condensation?

 

[Phil]

I had a leaking shower once that only leaked when the basin tap was used next to it (mains water) it dropped the pressure and caused it to leak more.

 

[Maryplumb]

Where was the leak? Lots of valves leak when turned on and off.
Was it on a heating system?

 

[JCplumb]

There's a house I've done a few jobs at, whenever you open the stopcock there's a temporary leak behind a toilet in the same room, it pees out too, the pipe goes from stopcock then behind the toilet into boxing, once fully open the leak stops. Customer says it's always been that way, I even used the toby to turn the water on and off but the leak still happens when turning back on.
Very weird, I'll have a proper look at it one day but the toilet needs to come out to get to it.

 

[sammathias]

Had a 25mm main leak when I turn external stoptap on but have internal tap closed...but have the internal tap turn on then open outside tap and no leak! Was baffling.