There are some municipalities that will not allow you to bond to the water systems, because of the possibility of low leakage currents eating away their old piping systems. I once worked on a project in Charleston, SC and at that time the local code would not allow bonding to their water pipes, and yes, we had to isolate project piping from their system. If gas and water companies used cathodic protection schemes on their systems, there might not be a problem. However, that will be very expensive and cost prohibitive to gas and water companies and would reflect in higher rates, which we don't want.
