I am confused about the house's main water supply grounding wires and the purpose. From here I read the following:
A jumper ground wire at the water meter is am important safety device that should be installed on most homes that have a buried copper or galvanized water supply line that brings water into the house. Buried metal water pipe makes a good ground for the electrical system and is commonly used for grounding the homes electrical system.
In most older homes the electrical systems are grounded from the electrical panel to the water supply line where it enters the house. This grounds the home’s water pipes throughout the house and is a good and safe practice that has been done for over a century. The grounding system in a home provides an easy path for electricity to flow to earth should a problem, such as a short circuit, occur.
Ok, so I get the reason to ground the electrical system to the water supply's copper pipe, but why is there a second black wire that jumps the meter?
Also, what happens if a large leak from the water valve were to short the ground wire? I'm not that knowledgeable about electrical stuff...