Howdy all, wondering if we could get some advice on an issue we're having with our burried 3/4'' pex-A main water line. A section was damaged by digging a few months ago and it was patched temporarily with a length of pex-a and sharkbite connectors. We're now coming back to permanently fix it using the appropriate pex expansion couplings and expansion rings. We purchased a Milwaukie ProPEX expansion power tool to use to expand the line ends. By inserting the 3/4'' size head, I gradually expanded the line end with an expansion ring seated on the end, slipped the coupling in, and repeated the same process on the replacement section of pipe with it's own expansion ring. After attaching everything and leaving for over 30 minutes, both connections were very loose and separated easily. We're not sure why the line and rings aren't returning to their original diameter and gripping the the coupling ends. Is there another stage to this process we're forgetting?

We then turned to a heat gun to warm the pex pipe ends with the rings until they became clear, and then inserted the couplings. This created a very mechanically strong connection. My 28 year old son could not pull off or rotate the couplings or rings at all once the pex cooled to room temperature. We had cut the damaged section of old line out to exactly 4' and cut a replacement piece also exactly 4'. However, after having installed the new section of pipe, we noticed that the new piece had retained a slight curve, since it had been stored in a bent position, and due to this one of the connections was pulling away and causing a gap to form between the flange of the coupling and the expansion ring. We tested it anyway in this condition and turned the water pressure back on, and there were initially no leaks or drips. However, after about a minute, we observed that gaps, roughly 3/8'', at both ends of the new piece had begun to form between the couplings and the ends of the pipe/expansion rings, and had begun to leak. We're mystified as to where these gaps came from, as the fit on one end had been perfectly flush before. We're also struggling to figure out how to straighten out the pex we do have, as it seems the slight curve is preventing both ends from seating correctly.

Any advice would be greatly appreciated!

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you need PROPEX fittings designed for the expansion system, NOT standard PEX fittings


you will need to cut a piece of PEX long enough so that it does NOT shrink and pull away from the fitting and/or shift the ring while it 'sets/contracts'

if you have a 4' gap, cut a piece 4'-4" and simply use wedges to maintain position in trench until the job is 'set'

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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We are still trying to get our older PEX A water line repaired that was damaged by our gardner when he was digging a hole. My son did buy PROPEX fittings designed for the expansion system. He cut a longer piece 4'1" of PEX and using the expansion tool he installed it with the rings and couplings as the instructional videos show to do. He let it alone for 30 minutes and then he turned on the water. Again there was evidence of the PEX slipping away from the flange on the fitting about an eighth of an inch. There didn't seem to be any leakage, so we left the trench open to check it this morning. There's a leak now at one of the junctures - a thin needle like stream of water spraying out. That connection has slipped a fourth of an inch from the flange where it's supposed to seat. It's the old PEX that is slipping off the couplings the most. The new PEX doesn't slip much, but it does slip back maybe 1/16 to 1/8th of an inch. Is that normal? We have heard that our water pressure here is a bit higher than normal. What else should we do to fix this line?

actual plumber on site to fix the plumbing

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

We are embarrassed to say that we now know why the fittings kept slipping off. We were using 3/4 size when the water line was 1 inch. These were sold to me at the plumbing supply store when I went in with a small length of the PEX tubing that we have for our water line. The store employee said it looked like 3/4 but it's definitely not. Will return for the right size...



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if it's 1" PEX not only your fittings and sleeves need to be 1", the PROPEX expansion jaw will need to be 1" too. I hope you can exchange for the right head instead of having to buy a new head and wasted money on the 3/4" head.

Thanks for posting the cause.