You have to find the break. Generally the water will come to the surface (pipes aren't that deep). Once you have the wet spot, the break is near by. Dig it out and fix the leak. Thye are only expensive if you don't fix it and let the system leak over a long time. If theleak is large, the wet spot will generate that much sooner.

I'm sorry but I believe you were fed BS buy the sellers. Why would anyone pay to have an additional service line and water meter placed so as to feed a "huge leak". Like I said, BS! The additional service was installed because the demand ( flow ) of the "extensive irrigation system" was to high for the exisiting service line and water meter ( happens all the time ). Perhaps work was performed on the property and lines were damaged and covered up by asphalt, concrete, gravel or other. I appologize, I'm really 'assuming' alot here. Maybe someone was that stupid.

Anyway. as you have already been told, you ( or someone else ) will have to turn the water on to find the leak. First make sure all the control valves to the irrigation system are turned off. Open the valve or valves at the meter and see if there is an indication of flow. If the meter is indicating that water is flowing then the leak is between the control valves and the meter ( upstream of the control vales ). Now you will have to leave the water on and wait until the leak shows itself, however this may cause damage if the leak is below the driveway, walkway, etc. If the water meter is indicatiing that there is no water flowing through the meter, then the leak is downstream of the control valves. You will need to be experienced to estimate what the flow should be for each valve station ( zone ) and then calculate what flow is going through the meter. There should be a considerable excess flow in the zone that is leaking. OR, if it is a "huge leak" the sprinklers or at least some of the sprinklers on the zone that is leaking will not be operating properly ( this is likely ). I would go through each valve station, one at a time ( turn off a valve before opening another ), to see if you can identify the leaking zone ( could be more than one ). Once you have confirmed which zone(s) are leaking you will have to cap off each riser ( remove sprinkler heads ) and turn on the control valve for that zone and then wait for the leak to show itself.

I really need to learn shorter responses, got to get back to work,

I hope this is of some help

boosterpumptech

Maybe the leak is before the meter, but after a curb stop? Or is after the meter, but before the house, making it 4-5 foot deep, and very expensive and destructive to replace the whole line.

I can see that situation occuring, if the main was left on and somehow froze. We worked on one last summer that required a hole you could have buried a volkswagon in.

Try turning it on, and looking for the wet spot. Then probe with a sharp steel probe to get even closer to the real leak. (when you find it, a little spring will come flowing out of your hole)