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The city service water line is 1" poly (blue; AWWA C-901). Currently it is connected to old copper with a compression fitting, then that copper is connected ~2ft later to even older galvanized with a failing sweat fitting. I would like to remove the copper and galvanized, and connect the poly directly to new 1" PVC. This section will be buried 18+ inches, then transition to new copper just before ground level, and then to new PEX-a under the crawlspace throughout the house. I have found various options for poly-PVC transition -- generally irrigation or other smaller pipes -- but none that speak directly to a buried main water line.

What is the best way to transition poly to PVC?

  • Barb x male thread for poly, secured with 1-2 worm gear clamps, and connected to female thread on PVC? Also use teflon + pipe dope.
  • Barb x female thread for poly, secured with clamps, and connected to male thread on PVC?
  • Universal transition coupling?
  • somehow reuse the existing coupling? Though I haven't seen anywhere that metal compression couplings can/should be used for PVC.
  • tap a new copper pipe into the existing coupling, attach a new sweat x female adapter, and attach PVC male here? This is not preferred, because I would like to reduce the number of total transitions. Also I'm having trouble finding 1" copper ferrules locally and hesitate to try and salvage the old ferrule.
  • something else I'm not thinking of?

Thanks!

existing poly to copper transition (compression coupling?) enter image description here

existing copper to galvanized transition w/failing sweat and beat up copper

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2 Answers 2

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The standard thing used around here is hdpe - a black poly ethylene pipe.

PVC is fairly brittle and it fails.

The hdpe has compression fittings which transition to threaded and you can go to brass or pex from there.

This is what it looks like coming inside through foundation wall from underground.

polyethylene to brass

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  • Yes, good idea. A compression fitting to internal thread is common in Australia. Any pvc has to be out of the sun of course, and follow local code as to wall thickness and size of overlap at the subsequent joins. Clamping the pipes either side of the fitting to a solid surface is also common to reduce stress on the fitting.
    – Polypipe Wrangler
    Nov 25, 2021 at 3:59
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Your first two options, six on the one hand, half-a-dozen on the other. Makes no difference.

Barb x male thread for poly, secured with 1-2 worm gear clamps, 
and connected to female thread on PVC? Also use teflon + pipe dope.

Barb x female thread for poly, secured with clamps, and connected 
to male thread on PVC?

Or skip the PVC and just use a double-barb union to more poly, and then "whatever" (probably barb to threads) for poly to PEX.

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  • Poppycock. The proper parts are 200PSI rated and I've dug up ones that have been working for 40 years (and not because they failed - usually because the pump needed to be replaced, and the well needed to be updated to come above ground level.)
    – Ecnerwal
    Nov 25, 2021 at 4:02
  • Stainless steel hose clamp made for the purpose, and any sensible person uses two on each barb with the adjusters on opposite sides of the pipe (so 4 for a barb union).
    – Ecnerwal
    Nov 25, 2021 at 4:05
  • Yes, worm-drive screw clamps, though your smart operator uses a nutdriver since the screw head is also a hex and it's much less annoying that way - the nutdriver does not slide off.
    – Ecnerwal
    Nov 25, 2021 at 4:12
  • There are different-but-similar products for irrigation (cheap, usually low pressure) and 160/200 PSI poly water pipe. Choose the right product.
    – Ecnerwal
    Nov 25, 2021 at 4:20

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