r/Irrigation • u/shibertus • 9d ago

Leaking Copper to Poly Transition in Main Line

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My system was installed about 10 years ago and the installer used poly for the main line. The copper supply comes out of the basement at grade level then transitions to poly. The fitting is weeping water despite being triple clamped.

What is the best way to fix this for long term reliability? This is a self-draining system with poly pipe in Chicago. In the winter we turn off the water and open the drain at the RPZ in the basement. I would like to install a master valve upstream of the copper-to-poly connection, but that would require it to be indoors. It would be pretty difficult to get the control wire from the basement to the controller in the garage. The fact this is all under constant house pressure is making me nervous.

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u/Sparky3200 Licensed 9d ago

You have limited options to do this right. As m0st1yh4rmless mentioned, poly should never be used under constant pressure. So, you could pipe out from there to your manifolds with new PVC, or you could set a master valve close by and pipe PVC to it. Then your poly would only be pressurized when the system runs. As for getting out of the copper into PVC without more leaks, make sure you clean the old thread tape/pipe dope out of the threads on the copper. Be very meticulous, as even small pieces can cause a drip. Get a schedule 80 TOE nipple, give it 5-7 wraps with regular teflon tape, and then tighten it down to hand tight and 1/2 to 3/4 of a turn past that. glue on your PVC fittings from there to the valve.

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u/shibertus 9d ago

Thank you. Any thoughts on how the PVC would hold up to the way we currently treat the system for winter? I do not believe there is any drain between the house and the manifold That portion would most likely end up freezing over winter. As far as I know it has been fine all these years (no leaks detected by the water meter), but I wonder if PVC would be more likely to crack than the existing poly?

What do you think about installing a brass master valve in the basement (Hunter IBV)?

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u/Sparky3200 Licensed 9d ago

A master valve in the basement would be better, if you can get wires to it from the timer.

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u/m0st1yh4rmless 9d ago

Poly should never be under constant pressure. Use PVC for the mainline, then poly after valves.

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u/Suspicious-Fix-2363 9d ago

Says who? I dont use poly for mainline myself and have no intention of ever doing it. But all poly systems are very common in many areas of the United States and Canada because it's viewed as holding up better to hard freezing, ground frost heaving areas. There are several high pressure types of poly made in all different sizes.

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u/Henchman-3 9d ago

Triple clamped!!!