Leaking underground. How do I locate the leak?

Discussion in 'Irrigation / Sprinkler Forum' started by Randyj, Mar 11, 2012.

  1. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    I've got about a 300 ft run of pipe that is leaking. I suspect a leak and have narrowed it down to about 50 ft. Would appreciate any tips on how to get extremely close to the exact location of the leak. I've got several ideas including injecting a dye or soap in the system. Just wondering how you guys would go about locating the leak.
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,004
    Location:
    NW Ontario, Canada
    What kind of pipe is it and does it have couplings? If it is a single contiguous length of pipe, you could make a pig and push it down the line with water pressure. The pig would stop at the leak and you could then measure the distance to the stopped pig with a snake.
  3. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    It appears to be all 3/4" PVC with tees for each sprinkler head.... so now I need to know what a pig is and how to make one. The leak is enough that the water bill has tripled and keeps a wet spot in the grass. Problem is that it is sloped and pretty much a drainage area between two houses so can't tell if the wet spot is from a break in the line or from property drainage. I've got a mechanic's stethoscope so thinking I can use that to listen for a leak. Just needing to load my arsenal of good trouble shooting techniques. I sure don't want to dig up the whole yard to locate the problem.... and I want to make sure it is a problem and not just something stupid like a bad sprinkler head or actuator type valve... I know a little about irrigation systems but it has been a long time since getting educated on them.
  4. Mitchgo

    Mitchgo New Member

    Messages:
    8
    Location:
    Seattle
    The 'pig' wouldn't work in your situation

    You may want to get a pro in... I've had so many customers who have spent hours doing what you are doing- I swoop in a find the situation in 5 min.

    Locating leaks for laterals-

    Step 1- Turn off all sprinkler heads / or dig up and cap all sprinkler heads- Utilize the water meter ( if applicable ) and calculate water loss- compensate 1gpm extra for leaking fittings. Let the zone run for 10 minutes or so and walk around looking for a wet spot. This really shouldn't be more then 30 min to 1 hour of work. For most situations this will cause the leak to surface unless it's running straight into a drain. Leaks happen much more often near the sprinkler head then elsewhere.

    At this point if you can't find it- more then likely you ARE NOT going to find it and you now need generalize the area of the leak instead.

    Step 2- If a wet spot doesn't appear the next step is to isolate- Try to find the middle portion of the the zone , Cut and cap and then utilize the water meter to see if the leak is on the first portion or second portion. A simple slip fix can repair this. Understandably this all depends on the zones design so use your best judgement. Do this one or 2 more times - try to isolate it into a small length of pipe. The best thing to do now is to re-route the pipe and abandon the section of the leak.

    Seems like you have gotten to this point? It's best to just re-route that 50' instead of spending more time to find the leak. I use My LD-12 to continue on to find the leak but that's not really available for a homeowner.


    Good luck
    Last edited: Mar 11, 2012
  5. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    Thanks. Fortunately there are ball valves at each end of the system and hose bibs. I can pressurize with air... so that may produce some indication of leak. I've considered injecting dish washing liquid or food coloring so that I could look for bubbles coming out of the ground or a red spot in the lawn... not too sure I want the red spot and not sure if the d.w. detergent would hurt the turf or not.... going to be raining tomorrow so just looking for a wet spot is not going to be the way to go for the next few days.
  6. Mitchgo

    Mitchgo New Member

    Messages:
    8
    Location:
    Seattle
    If the water isn't surfacing above your landscape/ lawn then why would bubbles or food coloring make it up to the surface. I don't believe that would work but good luck if you try.

    Using a high capacity air compressor with at least 50 CFM would probably show the leak right away.

    When I said wet spot I meant an obvious sign that this is the leak- unless it rains a crap ton you are still in the clear to do that too
  7. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    Thanks. We're headed out there shortly. I'll take some soap and stethoscope. We ran the water back in the fall and couldn't see an obvious place. It is a lake home with a pump at one end pumping water out of the lake and connected to public water system at other end. No info from previous to know layout other than obvious sprinkler heads and control box on wall.
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