Just to throw in a couple of alternate ideas from Merrie Olde England: [Linked Image]

On TN-C-S supplies, which are effectively like a standard American service where the house grounding system is bonded to the incoming neutral, there is no requirement here to use a local ground rod at all.

In practical terms, there's likely to be a ground connection due to the bonding of water pipes, but as plastic supply pipes are becoming more and more common even that is changing gradually.

In many rural areas of Britain we have a TT system, where there's is no neutral-ground bond, so the ground rod and earth is part of the fault path. The resistance can be considerably more than 25 ohms:
http://www.tlc-direct.co.uk/Book/5.5.2.htm