Plumbing question: How the hell does this happen?

I heard a strange sound just after 7pm tonight and I went to investigate. I must say that it's great fun crawling under the house, there's around 300mm of headroom and lovely sharp ant caps. Obviously the noise was located the longest possible distance from the access hatch as well.
When I finally got there though, I found this:



After a quick trip to Bunnings, followed by a lot of swearing, I managed to fix it and got the piece that I removed back inside.

Now my question is, how does that happen? I'm not near the ocean, so there's no salt, I've got RCDs, so I don't think that there was a current passing through the pipe. It's probably where a bit of condensation formed, but I would only expect a bit of surface rust, not crazy pitting like this.

 

Erosion Corrosion:

Erosion corrosion of copper water tubes - Wikipedia

pinkboy

 

Had a full bladder maybe

Usually the way, Murphy's Law
What Causes Copper Pipe to Leak/Fail? - Restoration Piping Technologies - Cincinnati, Ohio

 

This pipe failed from the outside in though, not from the inside out. Your link also says that a pipe might last 280 years and I didn't think that my house was quite that old.

Again, this more explains from the inside out.

 

I would say when they did the plumbing rough--in all those years ago when they bent the small section they fractured that small bend over time under constant pressure then this happens..

 

You've come off pretty lucky really (half glass full), imagine if you'd never heard it, or it was in the wall cavity etc

 

Possibly, yes!

Definitely! Less than $100 and two hours of work (including driving) is pretty bloody good for a water leak in my book!

 

Imagine if like many on here you didn't know how to diy it, evening emergency call out for a plumber $$$

 

Definitely, but being the cheapskate that I am, I would have turned the water off and waited until today.

Who needs to have a shower and brush their teeth anyway.

 

Unlike most tenants, that's the logical approach @spludgey - contain the issue, minimise further damage, fix it (or have it fixed at non-exhorbitant rates).

Pretty green - you know you're soaking in it.

 

I had this happen in a slab, prob just a weak spot and the expansion and contraction caused a pin hole.

I would say that one had a weakness, probably from when they were working on it initially and has taken years to finally fail.

 

there are many reasons for copper pipe to pit ,as in the links above

My guess - the green / blue copper oxide may indicate electrolysis
between the copper and the soil

Note the leak is on the part of the pipe that has been bent .
The leak is from the inside out

best way to fix is to cut out affected area and silver soldar or Bpress in a new piece of 20mm copper

compression fittings must not be used !

those pex shark bite push fitting are allowed in the AS ,
not ideal though

 

One of those things I dare say. Had a leaky pipe in the old place...as fast as I replaced a pitted leaky section a new one would develop. After 3 or 4 repairs in as many months I called a plumber who simply replaced the copper pipe from the meter to the house.

House was 30 yrs old so couldn't really complain.

 

is it the cold line? also does the copper go into the ground and if so is it lagged?

Cheers, Elives

 

Yes cold line and no lagging at all. It's PEX now, so hopefully it won't be any more problem going forward. I also ordered a pressure limiting valve that I'll install when it arrives.

 

I see, if it;s not lagged copper will corrode (when touching soil over time). you may have a small leak in the ground. have you replaced all the copper in ground?

Cheers, Elives

 

I didn't pull too much out of the ground, maybe 200mm. The soil around that wasn't saturated, so I think I only had one leak.
I just find it odd that the spot where it corroded was actually a fair bit above the ground.
I'm still thinking that perhaps an earth leakage contributed to it at some point. I did some quick calculations and changing it to the PEX should have added at least 2 M ohm to the system, so if that was partly to blame, it should no longer be an issue. I'll go under again soon to confirm that it's all bone dry. Or maybe I'll try strapping a camera to the cat first.

 

The cause is the Colgate Termite - tough teeth, grrrrr!

It's not so far fetched when white goods manufacturers exclude cockroaches causing issues with the wiring. - linky