Electrical grounded to the cold water pipe, usually before the first fitting once it is through the foundation..
ground
Hot water pipe rust first as compared to the cold water pipe for the same chemical composition of the water.
Because the mains pipe is buried in the ground where it takes longer for the cold to reach.
Depends where you are. In British Columbia, not required.
Cold water pipe.
The only problem that can happen is you would not have a ground for your electrical in the house if the pipe is cut between the clamp and the copper going into the ground outside. You shouldn't get shocked, if that is what you're worried about.
Using a water pipe ground clamp and securing the ground wire to the cold water pipe as it goes into the building BEFORE the water meter is one way. A better way is to drive an 8-foot ground rod into the ground and secure it via a ground rod clamp. My employer and I actually try and use both methods together.
To prevent an above ground water line from freezing, you can insulate the pipe with foam insulation sleeves or heat tape, keep the water flowing at a slow drip, and ensure the area around the pipe is well-ventilated and sealed from cold drafts.
The name for a pipe in the ground used to remove water from an aquifer is called a well.
DON'T CONNECT A GROUND WIRE TO A COLD WATER PIPE!!! Use ground rods in accordance with local codes. When in doubt, contact a local electrician or the local building and zoning office of your city or county. Connecting a ground wire to your cold water pipe can result in electrolysis that will eat away at you water pipe. ---------------- Metal underground water pipe is the first grounding electrode listed in the NEC. It is still commonly used in residential installations and is used in commercial installations when available. When the water pipe is used as the primary grounding electrode, it must be supplemented with another electrode which is most commonly a ground rod. Generally speaking, a 325 amp service requires 350 kcmil copper conductors for residences or 400 kcmil copper conductors for commercial installations. In either case these require a grounding electrode conductor of 1/0 ("one ought") copper.
Vent, return circulation
Your hot water pipe may be frozen due to a lack of insulation or exposure to cold temperatures in unheated areas of your home. Even though the water inside the pipe is hot, if the surrounding environment is cold enough, the pipe can still freeze.