Joining copper and PVC pipes

Why?  When you need to repair old pipes made of copper, you replace it with PVC (not for hot water) or CPVC.  When you install a plastic appliance on copper pipes or vice versa.

My main supply to the house is PVC, but the house pipes are copper.  So I need a joint at outside of the house.  There is another main supply to the irrigation system using plastic pipes.  But I need to install a heavy duty pressure regulator which is only available in brass.  The legendary pinhole leak of copper pipes happened at my house, and I had to replace that section in tight space that cannot use soldering.

Ideally you have a transition coupler with one side copper and one side PVC.  But you cannot allow soldering at the coupler because it will melt the PVC.  So there are unions and screw on the copper side.

If you do not need the flexibility of union , you just need a compression joint, which is also better than screw joints.  The gator grip is like a compact compress joint that can be used for copper and  CPVC, which has the same dimensions by design.  PVC dimension is different.  It is actually not a compression joint, since you only insert the pipe into the joint.

The gator grip is pretty awesome.  I cut  out the 1/2" bad pipe with pinhole using a very small copper cutter.  Insert gator grip on both sides, replace with  two CPVC sections with a CPVC union in the middle.  It sounds expensive with 3 gator grips and a union.  But calling the plumber with be many times over.

Actually it wasn't what happened.  The gator grip has on one side a screw head.  I use a flexible tube for tolet tanks with female screw head to join the two gator grips.  Lazy me.  And silly me - if I found that the CPVC union is in the other department, I would have tried the proper way.

All that doesn't matter for the 1" pipes outside of my house. There are just no size for it.  I had s screw joint for years, and I dissembled it and repaired the pressure regulator and then assembled it again.  It still didn't leak a drop.

The end of the PVC pipe has a male screw adapter.  The copper has a female screw adapter.  I reused the same joint after the repair.  I just put a thin layer of Teflon tape on the threads.  Not too thick because I don't know if it's beneficial when plastic screw  is involved.  Not too thin because if the materials expand at different rate, the tape is a good soft seal.

For the brass  pressure regulator on PVC pipes, you either use male PVC adapters or male copper adapters.  Since PVC screw adapters work fine, at least for male PVC, I use PVC adapters with a thin layer of Telfon tape.  No glue at all.  It saved a lot of trouble going from copper then to PVC.

BTW, my main pressure is well over 100, the house being on the hill.   That's why pressure regulators are needed, and that the screw joint is secure.