water meters

[Sam]

Hi,

This morning we saw a man from the water company walking down the street; at first we thought he was reading meters. Actually he lifted the "manhole"[*] cover at the end of each drive and put a metal rod down onto the pipe and listened to the other end of the rod. I am sure I have heard something about water companies listening to pipes but I can't remember where I heard this (tv or usenet?) and I can't remember what the point of it was. We were too shy to ask him ;)

Why would he be listening to pipes? Is he listening for leaks?

TIA

• I'm not sure manhole is the right word because to me a man hole has to be man size but you know what I mean, the cover over the stop tap at the bottom of the drive.

[Steve Firth]

Yes.

[Bob Mannix]

Yes, it's a very well established technique, also works for detecing worn bearings etc. Try it yourself, any old rod or stick will do. I fold the little flap in front of the earhole over the hole and put one end of the stick on that and the other on whatever metal you are listening to. You'll hear a water leak all over the pipe system in the locale, they will have been looking for where it sounded loudest, giving them a smaller area to dig.

[Derek Geldard]

An old "water man" said to me as a kid : If it doesn't stop it means there's a leak.

DG

[Mary Fisher]

It's a shame you didn't ask him. I asked one outside our house last year and he was delighted to tell me all about it, he said it broke the monotony of the job.

Yes, as others have said.

Mary

[Stuart Noble]

I've seen them wandering about town in the dead of night with their sticks. Presumably the only time it's quiet enough

[mogga]

What you need to do is form a homewatch for your street. Then you can waltz out and ask anyone you like what they're up to - as long as you're polite, smile and say you're with the homewatch most genuine workmen don't mind someone asking them. And the ones who do mind, well they should be reported instantly! ;-)

a mini man hole?

I've seen a water board bloke listening to the fence once - only cos the council had put the fence up on top of the line of the water pipes... he then dowsed his way across the garden and tracked the leak down to the huge water fountain erupting from the back garden. (Spectacular as the water pressure was spot on to get it to the 8th floor!)

[chrisj.doran]

Also, fewer people will be running taps, which as well as masking the actual sound of the leak reduces the local pressure allowing some leaks to close.

Chris

[Frank Erskine]

They're the night watchmen.

:-)

[Mary Fisher]

You don't need to form a homewatch!

Most people enjoy talking about what they do.

Mary

[Broadback]

Similar in principle to the wheel tappers. Fred the wheel tapper started off tapping train wheels one morning, changed 25 wheels before he realised his hammer had a cracked head!. Sorry old chestnut.

[The Medway Handyman]

Probably should be 'person hole' these days.

[The Medway Handyman]

I did some work a while ago for a lady who worked for the water company in the leak detection dept. They use ultrasonic scanners, listening rods and also apparently dowsing rods. She reckoned it did actually work.

[Derek Geldard]

What I've seen is they use a pair of microphones that straddle the leak by quite a few metres. They then apply a variable delay (positive or negative) to the signal from one microphone and subtract the signal fom mic 1 from mic 2 and tune for a null by varying the delay (and amplitudes).

They can then work out where the leak is.

I still have an open mind on dowsing.

DG