The building grounding electrode will always have current flow if the utility has grounded conductor feeding the building. The grounding electrode system places the earth in parallel with the grounded conductor. The better the grounding electrode system, the more current that will flow. As stated in other posts, a significant percentage of the grounded conductor current will flow on a common metal underground water piping system. This case is unique in that there is more current on the ground rod then on the water piping system. There must be an isolation joint on the water system, or the water main at the street is nonmetallic.Other than short duration fault current or lightning, etc... why should there be any current at all?