Strange noise from within wall All aspects of plumbing questions and answers, help, tips and information

[nmcl]

Hi. In the past week or so we've noticed a strange hammering/pumping noise coming from an external wall in our downstairs toilet. It's fairly low volume, but there constantly. The wall seems to be the point where the gas and water come into the house and maybe the electrics as well (not really sure how to tell that one). At first we thought it was a water leak, but it's way too quick for that as far as I can tell, and there's no evidence of a leak around the wall inside or outside. (The nearest equivalent I can think of is that it sounds like a muffled jack-hammer.)

I turned off the central heating in case it was related to the gas or hot water, but that didn't make a difference. I turned off the electric and the sound was still there. If I turn off the water (the stop-cock is about 2 feet from where the noise seems to be coming) then the noise remains once again. The only thing that seems to make a difference is if we turn the water pressure up full: the noise level increases as the pressure increases.

The house is old (19th century) but this bit of the house is a 1970's extension. Is it possible that there's some meter in the wall that's gone into overdrive and is connected to the mains so that I can't switch it off? (Gas, electric and water meters are elsewhere, so I've no idea what else it could be measuring).

I don't want to go ripping up the wall on a whim, but it's starting to worry me that that's what we're going to have to do.

Any help and suggestions would be appreciated.

[nmcl]

Coincidentally there's water coming through the ground in the car park next to our house. The water company were here yesterday to check if it was a leak or just water being pushed up from a raised water table due to the high rains we had last week. They said it was the latter, but the guy was good enough to come into our house and take a look (listen) at the noise. He thought it was definitely the sound of a leak and went outside to turn the water off at the mains; the noise remained and he said that meant the leak was between the mains and our house, probably in a pipe under the house!

Does this sound reasonable? They're coming back to try to locate the leak next week. Does anyone know how accurately they can do this (e.g., do they send a machine/mole through the pipes or do they just listen on the end of a long metal pipe?) I'm wondering how much of the place they're going to have to dig up to locate the leak and if they can't find it, where does that leave us?

[plumbbob]

Read this topic - it may help

https://www.diydoctor.org.uk/forums/viewtopic.php?t=8790

[Dave From Leeds]

Just a minute. If they turned your supply off outside at the main, there wouldn't be any water flowing between the mains and your house so if the noise remained I don't see how it can be a leak between the mains and your house. Since you are responsible for the pipes between the main and your house, the water company might be trying to get you to pay for something that should be their responsibility. Just my thoughts on the matter.

[nmcl]

[quote="Dave From Leeds"]Just a minute. If they turned your supply off outside at the main, there wouldn't be any water flowing between the mains and your house so if the noise remained I don't see how it can be a leak between the mains and your house. [/quote]

Yeah, that's what I thought, but the water company guy said that there would still be enough residual water and pressure in the pipes before the house to cause the noise if it was a leak. It still sounded suspicious to me, which is why I'm looking for questions to fire back at them.

[quote]Since you are responsible for the pipes between the main and your house, the water company might be trying to get you to pay for something that should be their responsibility. Just my thoughts on the matter.[/quote]

Yes, I agree. I've heard stories of screw-ups like what you mention where the home owner forks out the cash to replace the pipes only to find the problem wasn't a water leak at all, or was off property. I don't have a problem with fixing whatever is causing the noise if it's my responsibility, but I don't want to go tearing up walls and floors without a guarantee that they've identified the cause.

[nmcl]

I thought I'd let people know how this eventually turned out. Another guy from the water company came out yesterday and re-tested the water coming from the leak in the car park. He said that it was their water and he then went around with his pipe detector and found pipes that weren't on their plans. With a little more effort he found the leak and they came later in the day to fix it. The noise is now gone, so I'm pleased. Looks like the first guy didn't know what he was talking about.

Thanks to everyone for suggestions and comments.