Plumbing - water supply

[LonArcvarden]

Need help, again, from you wonderful, clever people.

On top of everything else that's going wrong for me, I think we now have a water leak.
I can hear a hissing sound of a water leak. I can hear it outside, close to the water meter, and up the road 100 yards away, I can hear the hissing sound everywhere in the garden, and in the house. It sounds very much like the hissing sound one hears when turning on the knob for the gas hob.
I've had our friendly local farmer remove the slabs on top of the water meter; the concrete cavity was flooded with water. (This was after several weeks of almost continuous heavy rain). He scooped all the water out, and watched the water meter. He said he 'doesn't think' the leak is on our side of the water pipe. (NB - it was dusk when he looked !). Which would be good; but I'm still not happy.
We had some friends come round, and as they've built a new house from scratch I reckoned he'd have a good idea about the water supply. He also lifted the slabs, couldn't hear the hissing sound (though his wife could) - but again he said he didn't think it was on our side of the water pipe, because the dial wasn't going round. I don't think he looked at it for long enough - and I'm still not convinced - because I can hear this sound, everywhere in the house, and late at night it's starting to get to me !!!

I've been checking on the thread about GdS under another heading on this forum. I'm becoming convinced (in my silly little mind) that what I can hear is the sound of a leak, under pressure, from the GdS which would be close to the chauffage-eau - yes ?
Having looked at one of the freebie DIY catalogues I can see, I think, how the water supply is supposed to work - but I'd be grateful if someone would just read through and confirm or put me right.
The water meter outside, with the dial, has a lever. If that lever is closed it means there is no supply of water to the house - yes ?
Now the GdS system; looking at that it would seem that there is a red knob on every one I've looked at, which seems to operate like a stop-cock.
If I closed off that control knob would that affect the water supply to the rest of the house; or does it cut off the water supply to the Chauffage-eau only ? At the moment, because I've been so worried about this leak I have turned off the main electricity supply (at the fuse board) to the chauffage-eau - so we have no hot water - called economising and saving electricity - and our money !!
The water pressure to the taps doesn't seem to be as high as it used to be; also when I've turned the electricity on to the chauffauge-eau (for about 12 hours) - and we've had hot water - the tank seems to run cold very quickly. Which is why I think the problem is at the GdS.
Yes, I accept - we need to call in a plumber, but I'm one of those people who likes to 'know' things anyway.

I hope I've explained the problem so it is understandable.... I'm just concerned about the cost of the loss of water - and the fact we're living 'rough' because we've no hot water !!!

As ever any advice, help, info would be greatly appreciated from you lovely people.

[princemeraj]

Turn all taps off in the house. Don't use the toilet or washing machine.

[ayawoalhassan]

I had a similar scare once, and the trick that helped me was turning off the house stop tap to see if the meter kept spinning; if it does, the leak’s likely between the meter and the house. I ended up calling a pro because the noise carried so far. I’ve used www.pm247.co.uk before for an emergency leak, and the quick response saved me a ton of stress.