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Newsletter Member Needs Help
 

 
Subject - Newsletter Member Needs Help

November 20, 2006  

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Newsletter Member Needs Help

Mike,
In December of 2005 I had two water leaks in my front yard, caused by pin-hole leaks in my copper water line. The leaks in the pipes were from the street to the house, thus the responsibility to repair was left up to me and not to the water supplier. My home is 4 years old and I do not understand why I should have such a problem with a newer home.

I called a plumber to repair the two leaks and from what he says it appears to be either a problem with bad copper piping or electrical current going through the copper pipes. Because I was not the original owner of the home, but the second owner, the builder said they were not responsible to repair the leaks. Remember, this was back in December of 2005. Well, this week my neighbors on both sides of me have encountered the same problem with water leaks. Although they have not had their problems repaired yet, the plumbers that have looked at their leaks do confirm that it is again, either bad pipes or electric current passing through the pipes. I do have a ground wire running from my electrical box and grounded on the inside to the copper water pipe line.

Also I have found out that all the wiring (i.e. phone, cable, gas, electric) is in a tunnel ditch going across the copper water line from the water meter to my house. I live in Kentucky were the building codes permit such utilities to be tunnel placed as such.

Mike Holt Comment: It's my understanding, based on studies by the American Water Works Association (AWWA), that alternating current flow does not create this problem. I'm willing to change my opinion if someone has a study to support the claim that pin hole leaks can be created in metal piping because of current flow. Do you have any thoughts?

 
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Comments

  • Hi Mike, I have seen this problem occur now and again in both the UK and in Australia. I would refer you to the 'Copper Develoment Association' docs on this:

    ************************** Alternating Current Action

    The role of alternating current on the underground corrosion of copper is not well understood.9 Some investigators contend that any metal dissolved during the anodic half-cycle should be redeposited during the cathodic half-cycle. Others believe that the efficiency of the anodic half-cycle is greater than that of the cathodic half-cycle and, therefore, that AC-induced corrosion can occur. The argument persists as to whether cuprous oxide on the outer surface of an underground copper water tube can rectify AC, although some of the recent research suggests that this rectification does not occur.10, 11

    Some investigators believe that a critical AC density must be exceeded for AC corrosion to occur.12, 13 It is also possible that AC facilitates depolarization of the local anodes and cathodes on an underground copper surface. 11 This depolarization would be expected to increase the corrosion-current density and the resultant corrosion rate.

    Until these differences of opinion are reconciled and recent research results are corroborated, it is reasonable to believe that the commonly used practice of grounding electrical systems to underground copper water systems can lead to corrosion. If the copper plumbing system is connected to a nonconducting main, such as asbestos-cement, some corrosion damage can be anticipated where the current leaves the copper, even if the current is alternating. Further, cuprous oxide could become semiconducting under certain conditions of soil pH and electrical-field intensity. Grounding of the AC system to the underground copper water tubing and unbalance in the AC system could very well be involved in the underground corrosion process.

    from: http://www.copper.org/resources/properties/protection/underground.html

    We resorted to disconnecting the 'earth' to the water pipe and providing a better ground by an earth electrode. Hopefully that is working. regards Roger Royal (Australia)

    Roger Royal
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