Any Plumbers around ?

[frumpety]

Only asking in case it is something I can easily resolve myself. I think I have a leak somewhere, I can hear water running constantly, my water bill has gone up by 50 %, but there is no evidence of a leak, so the walls/floors/ceilings are undamaged.
The noise is coming from the bathroom, near where the toilet is , can't hear anything in the airing cupboard where the hot water tank is and nothing in the loft where the cold water tank is, you can hear in it the downstairs toilet which is directly below the bathroom.
There has been no change in the water pressure and the boiler is working fine and was serviced within the last year , its less than 5 years old.
Any ideas ?

Hi Op
I had the sound of running water in our house but couldn't source the leak. I took out a homeserve plumbing cover plan at about £2 per month, and got them out. It turned out the leak was on next doors property and I could just hear the vibrations through the pipe on to our property.

I think we've established that it is the fill valve/ballcock in the cistern.

Take off the cistern lid and photgraph the things inside please.

i gather you can't see a service valve on the pipe that feeds the cistern. You are most likely looking for something like one of these. if there is a flexible pipe covered in metal braid it will probably be in the end fitting. All of these are turned off by turning the screwdriver slot so it lies across the pipe (not parallel).