Plumbing question: corrosion on copper main line - concern or no?

[Dan Friedrichs]

I was replacing a sink the other day, and shut the main water valve to the house (a gate valve), and when I went to re-open it, it broke shut Had to call the city out to shut the water off at the street (at 4pm on a Sunday...) and frantically replace the valve while the guy waited outside... Not fun!


I'm guessing the valve is as old as the house (mid-80s), so I'm glad to have replaced it with a ball valve.


But in the course of replacing it, I noticed the main supply line to the house is a bit corroded and discolored where it comes through the cement floor. I'm surprised to see nothing protecting the copper. The cement is also a bit "domed" up around the pipe, which I wonder if that's from corrosion (or just poor concrete finishing).


Obviously this is soft copper. In the course of replacing the gate valve, I definitely felt it bend just a touch when I was trying to un-stick the old valve.


Is this corrosion anything to be concerned about? I suspect not (it seems superficial, and I imagine this soft copper is fairly thick, and the 80's are not that long ago...), but I'd hate to be ignoring some warning sign that this is going to explode and flood my basement.

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[Christopher Herzog]

My two cents as an opinion as if it was mine. That to me is normal copper patina as it ages. I would not be concerned with the color.

Chris

[Bill Howatt]

Disagree it is normal copper patina, that's just dark copper brown, but it isn't totally unusual to see the blue on copper pipes. It is corrosion and it may be caused by something as simple as water from condensation collecting at the base by "falling" down the vertical pipe and collecting at the base on the floor. Supposedly embedding the copper in concrete should not be a problem and it is done all the time, IIRC.
I'd clean it off, examine the pipe and see if it looks sound. Found this, may help, but never done it myself. https://www.youtube.com/watch?v=MHXiCCCrkM0

[Tom M King]

Clean that off with Scotchbrite and if it’s not pitted underneath it should be fine. Looks like reaction to some kind of cleaner or something similar.

[George Bokros]

Clean that off with Scotchbrite and if it’s not pitted underneath it should be fine. Looks like reaction to some kind of cleaner or something similar.

or a small leak.

[Cameron Wood]

Couldn't you shut the water off at the meter yourself?

[Jim Becker]

Couldn't you shut the water off at the meter yourself?

He tried to...the valve broke in the closed position; hence, the need for the water company to turn off at the street so he could replace the main cutoff valve.

[Mark Wedel]

Depending on where you live, shutting the water off at the meter may be hard (the shutoff valve may be 4' down to be beneath the freeze line, so unless you have the special tool that reaches down there, not easy to do).

But in almost every jurisdiction, if you do that, and that valve breaks (which is possible, as it is not used often), you are now financially on the hook to pay for those repairs. Where as if the utility does it, and they break the valve, they will fix it for free. So there is reason to have the city turn it on/off if you can.

Now I did turn on/off the valve at the meter (in California, no freeze depth, so not far below soil line) to replace may main shutoff valve, but this is before I knew that if I had broken that valve, I would have been on the hook for money - with me knowing that now, I probably would have arranged with the utility to turn it off/on.

[Warren Lake]

borrowed the tool from a neighbour to turn the water off at parents. It was simple and easy. Likely you are right Mark that we are not allowed and likely I was told. Few years ago the thick very heavy copper main trunk going out through the wall in this home from 61 rotted out. There was one thinner section above the super thick elbow. All copper stuff still hole in it. Called and got a guy who didnt know, found an old guy who said its not possible to find a fitting to change to the black stuff and didnt listen., On the net found a Fernco fitting and they sent me an engineers drawing and it looked like it would work. Their fitting was perfect, high quality and dimensions bang on. Id like to change my main shut off as its an old turn handle and be nicer with a new clean ball valve.

[Cameron Wood]

Yes, I'm in California, and the valve at the meter is always accessible with a simple wrench, so it's good to be able to shut it off in a emergency, or for repairs as the valve at the house, if there is one, may not work well.
Sometimes the meter valve is stuck, and the water dept. can be called to get it working. I've never heard of the water dept. charging for a valve in 40 yrs as a GC.

A big deal has been made over being able to shut off natural gas in an emergency- it's the same for the water. Maybe not a risk of things blowing up or burning, but there could be a big flood.
A client just had a leak in the water line to their house- not catastrophic, but 400 gallons a day so a hit on the bill. They borrowed my water meter wrench until it could be fixed, which fortunately I didn't have to do as there was a lot of digging.

[Dan Friedrichs]

Unfortunately I'm in the frigid north - water meter is in the basement, and the street-level shutoff is 8' down under an access cover buried in the lawn (needed a metal detector to find it). The city guy had to PUSH on that long-handled tool to get the valve to budge, too - glad I wasn't the one putting that kind of torque on it.

[Lee Schierer]

Supposedly embedding the copper in concrete should not be a problem and it is done all the time, IIRC.
I'd clean it off, examine the pipe and see if it looks sound.

Unfortunately copper and concrete don't always play well together. Copper expands and contracts much more that concrete does so adequate precautions to handle the expansion and contraction of the copper should be taken. When cement comes into contact with copper, it can cause a chemical reaction that leads to corrosion. With their high alkalinity levels, cement and plaster can corrode copper pipes. The reaction between the two materials generates copper oxide which accumulates in the tubing and blocks it off. Both on its exterior and interior, this erosion will cause leaks or further damage to your plumbing system. Many municipalities require all underground piping to be encased in a polyethylene encasing wrap or a sleeving material.

[Jack Frederick]

I think you should be concerned about the pipe. I do not like the copper being in contact with the concrete. Get a catch bright pad and as advised, look for pitting.

[Dan Barber]

Unfortunately copper and concrete don't always play well together. Copper expands and contracts much more that concrete does so adequate precautions to handle the expansion and contraction of the copper should be taken. When cement comes into contact with copper, it can cause a chemical reaction that leads to corrosion. With their high alkalinity levels, cement and plaster can corrode copper pipes. The reaction between the two materials generates copper oxide which accumulates in the tubing and blocks it off. Both on its exterior and interior, this erosion will cause leaks or further damage to your plumbing system. Many municipalities require all underground piping to be encased in a polyethylene encasing wrap or a sleeving material.

Spot on Lee. That corrosion shown by the OP is pretty typical in most places where copper tubing is in concrete. I don't understand why it continues to be done. I know in certain parts of southern CA, slab constructed homes from the 80's are now having lots of copper plumbing failures. These days PEX is the way to go.

[Warren Lake]

when I concreted the new meter back in I put that foam you put on hot water pipes to insulate around the pipe then did the concrete. Not perfect as the mickey mouse club couild figure it out but it compressed a bit and was not the full thickness and I used the thinner of two that I had so no concrete on the copper home since gone. Used a burgandy scotchebrite on that and it will come to life. Friends used to do that in their mechanic shop the copper was polished up and nice