I am getting ready to pull an 220V/80A branch circuit to my new inside
heat pump. I am upgrading my 100A service to 200A locating the new
meter right next to the old one; and putting a new 200A load center,
then two branches; one to the existing 100A breaker box and another
branch circuit off the new 200A load center to the heat pump.

THE QUESTION IS:
I was advised to run a solid copper ground to my hot water heater, but
my water heater connects to everything with plastic pipe. I don't see
the point of running the wire to it.

I will be grounding the new meter; new load center, and existing load
centers to two existing ground electrodes right near the existing
meter. Since I already bought the 50' of #4 solid for the water heater
ground; I'll use that wire for this purpose
comments?