Copper corrosion under slabs is a big problem all across the country.
As a consulting engineer I made many investigations of these problems.
My experience led to three basic actions to avert problems.
Don't use copper water pipe as an electrical ground. The transient
currents can turn the pipe to Swiss cheese.
If the water supply tests for any level of hardness and CO2 [Carbon
Dioxide], the stray currents will cause an electrolytic erosion of the
copper, forming Copper Carbonate inside the pipe. This is easily
identified by the Turquoise color of the deposit.
Don't install copper pipe in soil that has been treated with salt or
Copper Sulfate to inhibit weed growth. This is a common practice among
subdivision developers, causing widespread leakage in new subdivisions.
I won't even mention the lawsuits that these problems have generated.
It is something that every prospective home buyer should check out.
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