# Locating underground water pipe



## isisdave (Sep 12, 2009)

Once more I come to TUG with an odd request, and I'll bet someone has an answer.

I need to locate the point at which an underground water pipe Ts, so we can install a valve on the two branches to isolate the two halves of the system.

It's 2-inch PVC and I'm not sure of the depth. It starts out only 18 inches deep at the meter, but it might be deeper at the point I need to locate it. I doubt that it's deeper than 3 feet, though. The T might be under grass, or under pavement.

The plumber says the standard method is to snake a wire through it, and then use an electronic sniffer to find the wire.  This will require either cutting the line to insert the wire, or partly disassembling a backflow device and putting it in there. And that will require turning the water off for an hour or so, which is difficult because this is the water supply for small business park. The point I need to find is about 100 feet away from the meter, and from point I'd have to insert the wire.

Is there another way? I can probably guess where the T is within 15 feet. I thought there might be some way to make noise in the pipe by inducing a large flow, and detecting the noise.  Some people think dowsing is useful ... is it accurate enough? Can any technique estimate the depth?

Thanks in advance for the input.


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## MULTIZ321 (Sep 12, 2009)

Are plans on file with the Water Dept?

Was a permit needed to lay the pipe?  If so, are plans on file with a local government agency?


Richard


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## isisdave (Sep 12, 2009)

MULTIZ321 said:


> Are plans on file with the Water Dept?
> 
> Was a permit needed to lay the pipe?  If so, are plans on file with a local government agency?
> 
> ...



There are plans, but I know they are not accurate. I have previously located (by digging) things that were not where they were supposed to be.


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## T_R_Oglodyte (Sep 12, 2009)

Experienced maintenance and operations people usually refer to "as built" plans as "not as built plans". I've also heard them called "storybooks".


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## AwayWeGo (Sep 12, 2009)

*This Calls For Water Witchery.*





-- hotlinked --​
-- Alan Cole, McLean (Fairfax County), Virginia, USA. ​


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## Sea Six (Sep 12, 2009)

I've had good luck using divining rods to locate pipes.  I use a heavy gauge copper wire (maybe 4 or 6 gauge) bent at a 90 degree angle, one piece in each hand, held out waist high with my arms also held at a 90 degree angle.  The two wires are about 18 inches long, with 6 inches pointing down, and 12 inches pointing forward.  Point the 12 inch length of wire directly forward, in the direction you are walking.  Walk very slowly, and when you cross the water pipe, the wires will pull towards each other in front of your gut.  It really works!  Don't grasp the wires - let them loose in your hands so they can swing around.


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## Talent312 (Sep 12, 2009)

My idea is to rent a trencher and circle the house, shutting off the water at the street first.


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## MelBay (Sep 12, 2009)

Where we live, before we do anything like this we're supposed to call 1-800-DIG-RITE and then gas, electricity and water all come out and mark the spots for you.  Can you call your Water dept., and see what magic they have available?


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## tompalm (Sep 13, 2009)

We had American Leak Detection come out and check for a leak.  http://www.americanleakdetection.com/

They hooked a pressure regulator to a spicket on the house and it put air into the pipes.  They listen for where the air goes and can detect down to five feet below the surface.  If your T is between the house and the meter, you will have a problem getting the regulator above the T. The air noise flows with the water.   They charged about $300, so it is not cheap.  

Also, a plumber traced our sewer line by removing the toliet and putting a transmitter into the line.  He pushed the snake for about 100 feet and a couple turns.  He could tell exactly where the pipe was and how deep it was.  

With a water pipe, you would probably have to turn the water off.  The only way to do it yourself, start digging, or rent some very high tech equipment.


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## stevedmatt (Sep 13, 2009)

MelBay said:


> Where we live, before we do anything like this we're supposed to call 1-800-DIG-RITE and then gas, electricity and water all come out and mark the spots for you.  Can you call your Water dept., and see what magic they have available?



This is the way to go. I believe it may also remove some of your responsibility. I think these are the numbers in CA, 1-800-227-2600 or 1-800-422-4133. If not, do a search with "call before you dig" and your area.


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## isisdave (Sep 14, 2009)

Thank you for all the ideas.

I have tried divining rods ... but not in the last 40 years.  Perhaps I will be better at it now than I was then.  

The utility locating services (a) start with plans, which, on public property, reflect "as built" not "as should have been built" conditions; (b) don't provide the service on your private property, except in a utility easement, which this isn't; (c) and in the case of non-metallic pipe, rely on the wire that an intelligent contractor buries next to the pipe so that it can be located later.

I thought there might be some technique based on noise from compressed air. I'll look into this, but I have an idea it won't be much cheaper than what the plumber proposed.   I'll also call the water utility and see if they have any great ideas.

Thanks again.


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