To help educate your customer, you might add that grounding to the water pipes _used_ to be allowed (the 5 foot restriction that iwire mentions is relatively new), but because of the very real chance that plastic pipe will be used in modern repairs, water pipes can now only be used in 5 foot section described.
You also may want to consider that running a new equipment grounding conductor is nearly as much effort as running new romex over the same distance, and given that this is old work, probably a T+M job. I'd strongly consider estimating the cost difference between running new ground conductors versus simply running new circuits.
-Jon
