Water humming noise

[Mizzy19]

Hi there.

Just wanted some advice.

I've recently started hearing water running noise in the walls of the downstairs toilet, utility and kitchen even when no tap is running.
The noise is only downstairs in those rooms stated.
The combi boiler was recently serviced and all functional. It's only a three year old boiler. Unsure if they did something to my pipework which could be causing this? As I can't recall hearing that notice before.
I turned my water stopcock off to see if noise disappears, the humming stops and it does. When I turn the water back on, humming, the running sound of water starts again in the walls even though no tap is on.
I'm concerned and noise is driving me crazy.
Any ideas of what the issue could be and what I need to resolve it?I'd appreciate it.

Many thanks.

It could be a leak on the service pipe from the main in the street. Ring your water company and see if they can check it out for you. They may check the mains in the street at the same time (although they tend to do that overnight when there's less background noise ).

Do you have a water meter? If so you could ensure all the taps if off and see if the little wheel in the water meter is still whizzing round. If so you have leak somewhere within your property..

OP we had a noise that sounds very similar and it was a leak!

NB just to add that even though you can hear the noise inside it doesn’t mean that the leak is inside - the sound of water can refer (echo?) through the pipes. The site of our leak proved to be about 30feet away from where it sounded the loudest. Good luck.

Don't have a water meter.

I had the boiler serviced a month ago and don't think I heard that noise prior to the service.
If I go under the boiler, I hear the same noise, of water flowing. But only if I'm under the boiler by the copper pipes. Otherwise don't hear that noise.
Could the boiler service guy have left a valve open or so?

I've checked for any leaks and can't seem to see any inside.

Is this an urgent matter or could I leave about two weeks as Plumbing and drainage cover starts then as cooling period finishes by then.

Thanks to everyone for their advise.