Pex adapter from water meter corroded and failed in 6 years

Glorious1 · December 22

My house was built 6 years ago. I had a bad water leak that was located by a detection company by the water meter. I dug it up. The leak was between the 1" pex and the brass (?) pex adapter that is screwed into the water meter assembly. When I took the pex off, I found the adapter had severe corrosion on the pex side, and even a pinhole that went all the way through.

I replaced the fitting and got things working with no leaks, but before I bury it again, I'd like to figure out what went wrong. I don't want to dig it up again in 6 years.

I assume that brass shouldn't corrode in such a short time. Could it be the builder used a cheap fitting that was made with the wrong metals? What could cause this?

Mad Dog_2 · December 22

What is in the surrounding soil? Mad Dog

Glorious1 · December 22

@Mad Dog_2 , I don't know, it just looks like mostly clay with a lot of rocks in it. None of the other meter assembly components seem corroded. Here's a photo of the repair in progress that shows the soil.

psb75 · December 22

Use a Uponor Propex stainless steel expansion fitting from Supplyhouse. There is something in the soil or water chemistry that is degrading the brass pex crimp fitting.

Kaos · December 22

This. Replace all fittings with stainless.

Also watch those crimp rings. Some are plated steel and will disintegrate in soil over time. You want copper or stainless rings.

ChrisJ · December 22

The fact that it's only eroded in one spot makes me think it was leaking. If something about the water did it wouldn't it be all around wherever it was in contact with the water?

bjohnhy · December 22

I would also wrap it so it's not in direct contact with soil.

hot_rod · December 22

Dezincification?

Screenshot 2024-12-22 at 3.34.52 PM.png

Glorious1 · December 23

Thanks for all the replies. I'm guessing it is dezincification. I assume all the other fittings on the water meter assembly (like the one the adapter is screwed into) are also brass, but no problems there. Maybe @ChrisJ is on to something, it may be related to a leak. All the corrosion is connected, and where the insert/barb portion meets the part that you wrench onto, it goes up that 90 degrees. Maybe they got some dirt between the pex and insert and that somehow started it.

Anyway, I found a stainless steel crimp adapter and ordered that. I will have to redo the whole repair when it arrives (sigh), but I don't ever want to dig it up again. The crimp rings are copper.

ChrisJ · December 23

Yeah...

Though there's a hole where the leak started so maybe I've got no point.

I didn't notice that before.

ScottSecor · December 23

@Glorious1, I doubt the plumber or the builder would "cheap out" on a buried water line. I suspect this would not be the place they would try to cut corners. Most likely, what they used what was readily available at the local supplier.

hot_rod · December 23

Pretty much all plumbing brass is DZR, dezincification resistant brass now, and also LF lead free or LL low lead

sometimes it is even stamped into the piece.

Maybe it was old inventory or an import that wasn’t certified DZR

Assuming the failure was dezincification, it looks like that was the cause.

The metals in contact are all similar, so electrolysis is probably out.
Could be aggressive soil, moisture would increase the attack

I would tape seal the copper crimp rings

mattmia2 · December 23

looks like it was leaking when it was installed and eroded. i can't see the inside very well but is it in good condition?

mattmia2 · December 23

i'd use ep fittings and expansion rings if those are permitted underground which i think they are.

i think the first ring of the barb wasn't sealed at all so water was flowing around that freely then the clamp channeled it where the groove and pinhole are and it eroded over time. stainless can be as bad or worse than brass with certain water chemistries especially those high in chlorides.

hot_rod · December 23

the meter yoke is copper and brass, i would use a brass adapter

The farther apart the metals are on the galvanic series, the more potential for electrolysis corrosion, especially in moist conditions

IMG_9268.jpeg

Glorious1 · December 23

@hot_rod, what kind of tape would you suggest to wrap the rings? I thought stainless would be safer, so ordered it. I hadn't considered the electrolysis issue. Maybe I should leave the new brass fitting, and wrap it in plastic wrap.

@mattmia2, yes, the inside of the old adapter is in good condition. It is coated with a thin layer of fine, off-white material that can be rubbed off. But there is no corrosion other than the one pinhole.

Intplm. · December 23

You can also use a plastic adapter to prevent this type of deterioration. Stainless is fine but not as readily available.

@Glorious1 you can use rubber tape found in the electrical section of your hardware store.

ChrisJ · December 23

https://forum.heatinghelp.com/discussion/comment/1828940#Comment_1828940

Technically stainless steel and copper / bronze is bad together.

hot_rod · December 23

I think Uponor had a shrink wrap sleeve they wanted you to use when you spliced a pex connection in a concrete pour.

I think shrink wrap with waterproof seal like you use on wire connections would be adequate.

I saw a video where they poured a liquid over the shrink wrap on a wire splice. Maybe some silicone liquid??

hot_rod · December 23

If you have pex "A" I would use expansion fittings. The repair coupling and adapter will cost you some pressure drop with the insert/ crimp ring type fittings.

Shrink seal that coupling also.

One of the brand names is where I would get the fittings. The inexpensive import brass is questionable, even with a known brand name on it.

Screenshot 2024-12-23 at 10.11.48 AM.png

mattmia2 · December 23

https://forum.heatinghelp.com/discussion/comment/1828975#Comment_1828975

I used a piece of collapsible discharge hose to isolate the gas riser in the concrete footing supporting the pedestal for my grill.

pecmsg · December 23

https://forum.heatinghelp.com/discussion/comment/1828975#Comment_1828975

nothing wrong with Heat Shrunk tubing wi seal the connection

mattmia2 · December 23

https://forum.heatinghelp.com/discussion/comment/1829086#Comment_1829086

other than that heat shrink in that size can cost anywhere from a dollar to $500 depending on where you buy it from.

Glorious1 · December 23

Well, thanks guys, but I'm going with silicone tape, which is recommended for underground fittings. It stretches so you can put it on tight, then it fuses to itself in a few minutes. Hopefully it will make a water-tight seal and prevent any soil contact. Also I rinsed all the soil off the areas I will tape, dried with paper towels, now air-drying.

pecmsg · December 23

https://forum.heatinghelp.com/discussion/comment/1829087#Comment_1829087

less then $25 for 4’ of 2”

Pex adapter from water meter corroded and failed in 6 years

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