In article , Bud-- wrote:

The NEC has for a very long time required that water service pipes be
used as a grounding electrode.

Note the word "a". Not "the".

The current code REQUIRES that water
service pipe with metal pipe underground length of 10 ft or more be
included as a grounding electrode.

And it flatly prohibits using it as the *only* grounding electrode.

Because this pipe may in the future
be replaced with plastic pipe, a supplemental electrode is required -
usually ground rod(s).

You have things backwards. The ground rod is the *primary* grounding
electrode, and the water piping is the supplemental electrode.

You're also wrong about the reason.

"Bonding of piping systems... the basic concept is to ground any metal pipes
that would present a hazard if energized by an electrical circuit." [National
Electrical Code Handbook, Section 250-80]

I don't know how to put it any simpler than that.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.