The answer to 'how does water line work' is that a water line is the main pipe that carries freshwater from the municipal water supply or a private well into a home. The water line runs underground from the street or well to the home, and it connects to the home's internal plumbing system to provide water for various household uses.
The water line is typically made of copper, plastic, or galvanized steel, and it is buried several feet underground to protect it from freezing temperatures and other environmental factors. The line includes a main shutoff valve, usually located near the home's foundation, which allows the homeowner to turn off the water supply in case of a leak or for maintenance work.