# Copper leaks under a slab



## user2090 (Sep 26, 2009)

This am I get a call from a customer where just a few months ago I made a repair on a 3/4 inch cold copper line, seems there is another leak. Thankfully we were able to fill the hole with pea gravel, and as such it was easy access. Leak was on another 3/4 cold water line, very similar to the last one. 

For the slab leak experts, what could be causing this? There is no obvious stone, pinched line, or anything like that. Also, it's not like we don't have plenty of copper in slabs here. The house is only 15 years old. 

Thankfully in this situation it will be easier to run new pex lines in the wall and eliminate that copper. I'm also exploring option to get away from any in slab copper altogether.


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## RW Plumbing (Aug 16, 2010)

Was the line insulated? If not, the salts and acids in the ground will eat the copper. Just like if you touch an uninsulated copper directly to cement the acids will eat the line. Also what type copper is it? Round these parts, only type K underground.


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## ToUtahNow (Jul 19, 2008)

Indie said:


> This am I get a call from a customer where just a few months ago I made a repair on a 3/4 inch cold copper line, seems there is another leak. Thankfully we were able to fill the hole with pea gravel, and as such it was easy access. Leak was on another 3/4 cold water line, very similar to the last one.
> 
> For the slab leak experts, what could be causing this? There is no obvious stone, pinched line, or anything like that. Also, it's not like we don't have plenty of copper in slabs here. The house is only 15 years old.
> 
> Thankfully in this situation it will be easier to run new pex lines in the wall and eliminate that copper. I'm also exploring option to get away from any in slab copper altogether.


What is the water source? In addition, if you could take a oicture before and after sectionalizing the pipe it may be easier to help.

Mark


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## user7551 (Oct 21, 2011)

How bout the iron content in the dirt if its not sleeved?


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## Mississippiplum (Sep 30, 2011)

Water source is important 

Low ph
Hard water
High H2S 
High clhorine levels 
Etc.
Will eat copper.

sent from the jobsite porta-potty


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## voltatab (Jan 2, 2010)

Mississippiplum said:


> Water source is important
> 
> Low ph
> Hard water
> ...


I thought HIGH ph was in addition to your list. But all the others are absolutely true.


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## Mississippiplum (Sep 30, 2011)

voltatab said:


> I thought HIGH ph was in addition to your list. But all the others are absolutely true.


High ph won't eat copper but low ph (anything below 7) will eat copper.

sent from the jobsite porta-potty


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## voltatab (Jan 2, 2010)

I am almost positive that too high a ph will cause problems as well, like above 8 or so.

Actually I believe hard water is water that's ph is too high


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## ILPlumber (Jun 17, 2008)

Is the leak below the slab under soldered fittings that are just above the floor?


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## Mississippiplum (Sep 30, 2011)

voltatab said:


> I am almost positive that too high a ph will cause problems as well, like above 8 or so.


Naaa, we have a ph of 8.5 on most of our wells and copper lasts 25-30 years easily. 
The higher the ph the better. Below 7 and you better be installing a neutralizer.

sent from the jobsite porta-potty


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## Mississippiplum (Sep 30, 2011)

voltatab said:


> Actually I believe hard water is water that's ph is too high


Nope, not at all

sent from the jobsite porta-potty


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## voltatab (Jan 2, 2010)

Well alrighty then.

Actually you are right, my bad


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## Mississippiplum (Sep 30, 2011)

Ph has to do with acidity

You can have water with 100 grains of hardness and a ph of 6.

sent from the jobsite porta-potty


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## RW Plumbing (Aug 16, 2010)

I always thought that a 7 on the Ph scale is neutral. Lower than 7 is acidic and higher is basic. I thought it was primarily acids that effected copper negatively.


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## CTs2p2 (Dec 6, 2011)

Nope Mississippi is spot on.. 

Low pH Is acidic and high pH is an alkaline.. 7 is neutral


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## CTs2p2 (Dec 6, 2011)

Lime is sometimes added to municipal waters to lower pH in turn raising the hardness if that's where the confusion comes in?


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## CTs2p2 (Dec 6, 2011)

Back on topic... 
I've seen pin holes in copper with good water chemistry, where there is a large usage, undersized, or hot line with constant recirc. 
Turbidity Usually just past a fitting, tears the inside of the copper right out, this is why we ream copper pipe..


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## Mississippiplum (Sep 30, 2011)

Yes, also on calcite systems used to raise ph the hardness is raised just a tad. 

Ph Is effected by acids in the water.

sent from the jobsite porta-potty


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## Mississippiplum (Sep 30, 2011)

CTs2p2 said:


> Back on topic...
> I've seen pin holes in copper with good water chemistry, where there is a large usage, undersized, or hot line with constant recirc.
> Turbidity Usually just past a fitting, tears the inside of the copper right out, this is why we ream copper pipe..


Very good point!!!

sent from the jobsite porta-potty


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## user2090 (Sep 26, 2009)

To answer the questions. 

Water is from city. Uncertain of ph, or what they add for treatment. 

Copper is type L, under a slab, no fitting. Both holes have been part where pipe is in dirt and pea gravel. 

I'll grab some pics tomorrow.

Also, both holes are on cold water lines.


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## Mississippiplum (Sep 30, 2011)

Flux corrosion? 

Hopefully protech will be here soon, he knows this shiot like the back of his hand.

sent from the jobsite porta-potty


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## Mississippiplum (Sep 30, 2011)

Indie said:


> To answer the questions.
> 
> Water is from city. Uncertain of ph, or what they add for treatment.
> 
> ...


Do a ph and hardness test also

sent from the jobsite porta-potty


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## user2090 (Sep 26, 2009)

Mississippiplum said:


> Do a ph and hardness test also
> 
> sent from the jobsite porta-potty



I will so long as my kit is ok. I will also try and remember to cut out that leaking piece in good enough shape to look at it.


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## Anonymous (Jan 7, 2012)

High PH above 8 will eat brass....


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## Protech (Sep 22, 2008)

Hard to diagnose without seeing the copper and knowing the water chemistry.


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## 3KP (Jun 19, 2008)

I'll go out on a limb here...

When water travels through the copper pipe is sets off a little vibration in which will rub against the peafill. Over time even a smooth rock with a little movement will cause a hole as it rubs over a surface..

I not sure what causes it I hate fixing them but love the monnies it brings in for such little material involved..


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## PlungerJockey (Feb 19, 2010)

We repair alot of slab leaks here in NW Arkansas. I'll give you a brief history. Almost all the slab leaks I deal with are in hot water lines. And 90% are in homes built from 1988 till 1998. 

Up until 1988 all builders filled their slabs with creek-bed gravel. Sometime in 88 the EPA stepped in and said "no more". It was killing fish and upsetting the ducks.

From 1988 - 1998 all builders started using limestone based gravel. The plumbers were installing copper directly into the slab (coated copper did not exsist). The cheap thin sandwich plastic sleeve was required a short time later, but it is useless. The copper in contact with the gravel just gets ate up.

I have seen several rolls of bad copper that was should during the housing boom here. It was sold around 2005 and is riddled with pin holes. I'll be fixing that stuff til I retire.

I have also seen houses hit by lightning, develope slab leaks.

There thats everything I know about slab leaks. :jester:


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## Titan Plumbing (Oct 8, 2009)

We have lots of slab leaks here and we backfill with either cushion sand or native soil.


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## Epox (Sep 19, 2010)

I use the poly black utility pipe to sleeve piping in. It's also great because old piping can be pulled out and new slid back in. Often avoiding over head runs. Type K 3/4 can be a PITA to pull in longer runs though. I use a high lift jack and chain.


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## RW Plumbing (Aug 16, 2010)

We use that black armaflex insulation on copper underground. Not as good as a pipe sleeve but much easier to work with. I would think the lack of protection on the pipe has something to do with this.


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## OldSchool (Jan 30, 2010)

3KP said:


> I'll go out on a limb here...
> 
> When water travels through the copper pipe is sets off a little vibration in which will rub against the peafill. Over time even a smooth rock with a little movement will cause a hole as it rubs over a surface..
> 
> I not sure what causes it I hate fixing them but love the monnies it brings in for such little material involved..


Most wear on pipe is do to expansion and contraction from temperature change

Sent from my portable office....yes I am at work


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## Associated Plum (Nov 4, 2008)

PlungerJockey said:


> We repair alot of slab leaks here in NW Arkansas. I'll give you a brief history. Almost all the slab leaks I deal with are in hot water lines. And 90% are in homes built from 1988 till 1998.
> 
> Up until 1988 all builders filled their slabs with creek-bed gravel. Sometime in 88 the EPA stepped in and said "no more". It was killing fish and upsetting the ducks.
> 
> ...


Donna Fill was also used and is a by product of crushed granite and is what we find the majority of slab leaks buried in.


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## Tommy plumber (Feb 19, 2010)

OldSchool said:


> Most wear on pipe is do to expansion and contraction from temperature change
> 
> Sent from my portable office....yes I am at work


 






I thought it was gremlins.......:laughing:


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