Bob I agree also. I think aldav53 is a bit unclear as to the purpose of grounding hence the confusing question.
The "ground" is not current carrying. The unbalanced and fault current is carried by the neutral conductor that connects to the transformer center taps and runs from pole to pole and into every service.
This neutral is grounded at each service (through ground rods and bonding to the water line) as well as at each transformer with a ground rod. The purpose of grounding is to offer some protection from lightning and primary power crosses as Bob points out.
If the area has a continuous metallic water system, yes the pipe is, in effect, in parallel with the neutral on the poles and also in contact with the earth providing a ground.
-Hal
