I wouldn't think the gas is better than the ufer.
The gas is wrapped in 3M tape and the ufer ties to several hundred feet of rebar in the footing. But I could be wrong and will check. I'll check for dissimilar metal connections as well.
I suspect chemical erosion of the copper lines by the water softener. The water softener salesman wants to sell her a $700 filter to remove the copper from the water. That's why she talked to her contractor friend and on his advise called me.
I can't confirm 25 ohms at the ufer but what I've read leads me to beleive the resistance of a ufer system is going to be about as low as I'm likley to get. Worst case is to drive 1 additional rod and call it good. All bonding wires originate from the sub panel ground bus as does the buildings GEC. There are no other bonding jumpers other than mixing valves. To my knowledge the only point the copper goes underground is at the kitchen island.
There are also 2 on demand gas water heaters, one at each end of the house. One of them uses a 120V igniter and the other uses flow to generate its own ignition source. Maybe some bonding going on in there? I'll check everything I can think of in the morning.
