Building codes address grounding. New construction in most cities require copper clad 8 foot grounding rods. This means the steel rod must be driven into the soil eight feet. The reason for this is, a short rod with dried earth around it does not act as a ground, the reason for driving it down eight feet where there is moisture.
As stated, older homes were grounded to the water lines, most still are. However, if you have had changes in plumbing from metal to PVC plastic pipe, then you may not have a ground on the water line.
Even a few years ago, brand new homes being built in Plano TX, north of Dallas, the contractors actually grounded to the gas lines in a subdivsion. Well, you guessed it, lightning struck one of the million dollar homes, exited the gas line causing a huge fire that destroyed the home. The home owner went after the nautral gas company.....when it was their contractor. The City of Plano changed their building ordinance immediately following the discovery that the builder had grounded to the gas line.
Live and learn.
D in TX