# locating underground sprinkler lines



## denemante (Apr 2, 2010)

I want to store 2500 pound pop-up camper in my backyard. Other times, I have the need to get a pickup down there with firewood, dirt, etc. I also plan to have a shed delivered.

I know where my sprinkler heads are. But how can I determine where the lines are? I assume they are PVC. Don't know how deep they are - but I'm guessing the weight of a truck over them wouldn't be good.

Some have suggested a dowsing rod - but I thought that was a myth/superstition.


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## cibula11 (Jan 6, 2007)

I wouldn't think the lines would be a problem...just locate the heads. The truck would have to sink significantly to damage the lines....you could lay down sheets of plywood and park on them, which would displace the weight a bit.


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## titanoman (Nov 27, 2011)

I've used a vining rod (2 coat hangers) several times. They work.


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## denemante (Apr 2, 2010)

I know where the heads are and would stay away from them. Are you saying you think it would not harm them to drive over them?

And secondly - the vining rods - two L shaped metal hanger held pointed slightly down - when I pass over the water, they'll move or point? Just from the water in a 1 inch line?


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## cibula11 (Jan 6, 2007)

denemante said:


> I know where the heads are and would stay away from them. Are you saying you think it would not harm them to drive over them?
> 
> And secondly - the vining rods - two L shaped metal hanger held pointed slightly down - when I pass over the water, they'll move or point? Just from the water in a 1 inch line?


It would help to know how deep the lines are. They should be well under the sod layer (3 inches or so) and probably more like 6-8 inches or better. I can't think that a truck would sink that far unless it is REALLY soggy. Not sure what the depth requirements are on sprinkler lines...had a buddy that was going to put a paver patio over his, and was just going to have to move the heads...knowing the depth of the lines now would help.


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## jasonreck71 (Jan 14, 2012)

titanoman said:


> I've used a vining rod (2 coat hangers) several times. They work.


I was in the sprinkler business and this is how I did it. I found that this usually got me within about a foot. I would guess your lines are 8-12" deep...I wouldnt worry about driving over them, I had a 10 ton well truck drive over all my lines, no issues. Obviously don't drive over the heads


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## RegLearning (Oct 23, 2011)

its called witching.. lol it works quite well. unbelievable for sure but works great.


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## elessar007 (Feb 2, 2012)

Its a longshot, but whoever installed the irrigation system might actually have a map on file. This would be especially true if the system was put in when the house was new before anyone bought it. If you can, contact the builder and you just might get lucky. Divining rods might work but you could also try a less esoteric method by making a map of your irrigation system for future reference. This would be important if you ever sprung a leak because the rods would only point to where the water collected not where the leak is.
Create a map by making a rough sketch of your yard. On the sketch, include the location of the heads and be sure to label what zone the heads are in. Next you can dig _carefully _with a hand trowel around the heads to get the general direction of the line. Put a stake near each head and valve and use string to mimic the irrigation lines. Connect the stakes based on the direction of the lines that you learned by digging around the heads and that the layout will most likely be as simple as possible in order to maintain pressure and conserve materials. Provided they didn't use a lot of funny pipe, it shouldn't be to hard to infer the layout of the lines using some stakes and string. Obviously nothing beats actually seeing the lines themselves but you don't necessarily have to dig up your entire yard just to map the irrigation lines.


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## Gary in WA (Mar 11, 2009)

I use rods all the time to find: my clay drain tiles 6' underground- dry inside (water not required); electric power cable to house-5' down; plastic drain line; re-bar in slabs; plastic water line, cable tv line; any wires; city sewer drains- 16'-24"; copper pipes; any pipes (it needs to be man-made that isn't found underground- normally). Best is heavy gauge ground wire from box store, 18"- with 6" right-angle bend. It will swing/move like a magnet to the object as you pass over it, 12" above ground. Oh, and sprinkler lines, empty or full...LOL.

Gary


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## wrooster (Apr 16, 2010)

denemante said:


> I know where my sprinkler heads are. But how can I determine where the lines are? I assume they are PVC. Don't know how deep they are - but I'm guessing the weight of a truck over them wouldn't be good.


Common sprinkler lines are 3/4" or 1" black polyethylene pipe. Some smaller yard applications use CPVC (bell end) water pipe, in same diameters as the poly.

In the case of poly, it was pulled in using a vibratory trencher (Ditch-Witch or equivalent) to a depth ranging from 6" to 12". 

If this is the case, there is no problem with "reasonable vehicular traffic" over the sprinkler system. You are not going to crush 1" pipe buried 6" (+) down with a 4000 pound pickup truck.

Wrooster <-- ex-sprinkler installer. :thumbsup:


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