If you blind yourself to everything else and read this: "250.53(2) Supplemental
Electrode Required. A metal underground water pipe shall be supplemented
by an additional electrode of a type specified in 250.52(A)(2) through (A)(7)."
It might sound as thought an underground water pipe were the MAIN GROUND electrode, all others were extra.
As to the original question, I can not think of anywhere that would not want it bonded, if not part of the electrode system.
And only time I think it would not be considered part of the electrode system is if it had a water meter less than 10' away.
As far as local practice:
Water GEC is sized for service - always!
(2) rods as supplimentary electrodes
Load side of gas meter bonded to service or electrode system.
And hot water at the point nearest origin and continuous to the electrode system cold water at nearest point. (Like at the water heater.) Used to hit the gas there too, until a few years back.
And yep, different places require different things as far as this goes.
Saw some commentary in the code about this:
There has always been uncertainty as to whether metal water piping systems should be used as grounding electrodes, so many years ago the electrical industry and the waterworks industry formed a committee of all interested parties to evaluate the use of metal underground water piping systems as grounding electrodes. Based on its findings, the committee issued an authoritative report on this subject. The International Association of Electrical Inspectors published the report, Interim Report of the American Research Committee on Grounding, in January 1944 (reprinted March 1949).
The National Institute of Standards and Technology (NIST) has monitored the electrolysis of metal systems, because a flow of current at a grounding electrode on dc systems can cause displacement of metal. The results of this monitoring have shown that problems are minimal.
Maybe they are still arguing about it somewhere?
[This message has been edited by e57 (edited 06-01-2005).]