> the idea of clamping electrical ground to your metal water pipes
Underground metal pipes ARE grounded.
100 years ago there was the idea that electric power should "float".
It is easy to prove in a lab that you can grab either side of a floating electric circuit while standing on ground (or touching the sink), no shock.
Problem (as experienced electric techs knew) is that a real-world electric circuit *always* has grounds. Transformers leak, and in a large system the leakage is non-negligible. Trees grow into the wires. While you grab a sink and one side of the line, someone else is grabbing the other side of the line.
There's also lightning, which in the end virtually mandates redundant to-dirt bonds to limit damage in a lightning hit. (Even for underground wires, because they connect to wires up in buildings.)
In many places the power company is responsible for supplying a good ground. Even so, I know that in the UK the installer is also supposed to bond to the water entrance.
In the US the power company feed is grounded but we do not rely on it. Service entrances must have their own to-dirt bonding. When water lines were always metal this was an excellent Ground; also an electric-water bond ensures that the then most popular shock (to kitchen sink) is as mild as possible: either zero or 110V, not stray leakage to high voltage.
Yes, there have been decades of back-and-forth bickerings between the water and power interests. Bad connections kill water technicians. However bad grounding can harm many more non-technical non-employee people, and water-techs can be trained to jumper-around where they are working, so bonding to water entrance is generally accepted.
Which is becoming moot now that much water piping is plastic. At the old house I faithfully bonded my inside copper pipes to the city-water entrance. Then I learned that the "new" (1980s) line from the street was all plastic except the foot where it went through the foundation. Not a good ground, though just enough to pass a fatal shock.
Bonding to gas pipe is more debatable. Nevermind the dead gas-techs, heavy current in a gas pipe "could" blow-up the whole neighborhood! Most gas associations permit it, most gas-techs do not want it; but the last guy who yelled at me, it turned out the gas line was all plastic. The only bond between gas and electric was the thin flex-hose to the boiler, and that would be a bad place for an electrical fault. Better to have any electric leak through a #8 at the entrance.
Where known-metal underground pipe is not available, NEC suggests one dirt-rod tested, two dirt-rods un-tested, large buried plate, buried wire around the structure, or electrode in concrete foundation or slab. Even where hardly-effective (my thin dirt on rock), there's no reason NOT to dirt-bond ALL touchable metal in the house.
