tom baker said:
Only if the GEC is a metal water line continuous to the street main and other houses, and yes there will be a small percentage of the neutral current. Most water service lines are not metallic, plastic has been used since the early 1970s.
You would have significant current on pipes like this. But even if you just have rods and plastic pipes, the rods are a return path to the transformer and current will flow on it. Much less current though, because of the high resistance of rods compared to low resistance for solidly connected wires and pipes.
I don't think you'd be shocked by holding a disconnected GEC as long as the service neutral is solidly connected. Yes, current flows through it, but the voltage is low (should be equal to voltage drop in the neutral). Would you be afraid to touch a car jumper cable jaw with hundreds of amps flowing through it? Not enough volts to get your attention, but lots of amps.