In a standard service, there is usually a cold water copper pipe that grounds the service. Generally it is located fairly close to the service disconnect.
I will agree that if the coldwater pipe connection is not close to the service disconnect, that ground rods will help to keep the surrounding area in the same potential as the disconnect/system.
But as a supplement to the system in general it is not altogether very effective. That is why I would like to see that a concrete encased (footing) electrode become mandatory for all new installations. I believe that there are some jurisdictions requiring this.
Pierre
