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Mikeron =
"...Surely if the water meter is removed the house is still ground..." = yes
"...What is the reason for having a jumper wire in this case?..." = As joed said, if the water meter is removed for service, the house's upstream copper wiring is not bonded to ground. Additionally, a water meter may the
electrical viewpoint as being "dielectric", that is, non-conductive. Of course, we would suspect that it indeed is.....but it may not be build intended for the conduction of household AC currents.
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FrodoOne =
"...One would hope that it comes from the main "Ground Stake"... = This is the main service ground. Here in NA, we use the metallic incoming water pipe, not ground rods for system grounds (of course, this is for urban homes, not rural where pressurized city water service is not available).
"...is actually an "equipotential bound"..." = no, its not. It's the main service ground.
"...Is this a home inspector or an electrical inspector?..." = Excellent question. I'd like to know too. You can't ground pex......surely even a home inspector knows that.