My 1970 house with slab foundation originally had a connection to the copper water line as the only ground. I had a pair of ground rods 6' 6" apart added and would like to disconnect the ground to the copper water supply pipe. Is this allowable and advisable?
The reason I would want to do this is to save the water pipe from damage. We had 20 pinhole leaks in a vertical vertical hot out from the hot water tank. This tank was sweated copper tubing all the way to the tank (advice from city plumbing inspector 25 years ago) instead of flexible supply lines with insulating connections.
There is at least the possibility that the pinhole leaks were due to electrolysis from dissimilar metals (steel tank-copper water lines). Twelve years ago I had the tank replaced with a tankless heater connected with insulated ("dielectric" connections). I want to eliminate the possibility that the ground rods might produce a similar effect in the copper tubing.
Also, I have heard of lightning strikes damaging copper water lines if the panel is grounded to the copper pipes.
If it is OK to disconnect the ground wire to the copper water supply line, should I do this in the panel and at the pipe? Is it OK to leave the old ground wire in place in the panel but disconnected from the ground bar?