It's a situation like this that highlights some of the confusion the code has in it, especially in Article 250.
After all, just what are we attempting to accomplish with that wire? The ground rod / ufer / whatever only requires a #6, regardless of the service size.
Clearing faults? Is there ANY possible circumstance where the plumbing could possibly be exposed to the full service fault current? Does it ever make sense to require more copper in the wire than there is in the pipe itself?
I think we're wrestling a dinosaur here .... the water line once was the grounding electrode, yet today we're -at most - using it as a supplementary electrode. More realistically, we are bonding the pipe, to protect against it being accidentally energized.
Still, no harm done .... and until the code panels get their acts together (maybe even get an grammar expert involved), engineers will be stuck specifying idiocy.
