What is the term used for the shutoff valve located in the main supply line inside a building?

The term commonly used for the shutoff valve located in the main supply line inside a building is typically "Main Line Valve." This valve plays a crucial role in a building's plumbing system, allowing the entire water supply to be shut off for repairs, maintenance, or emergency purposes.

By having this valve in place, it enables swift control over the water supply, ensuring that leaks, blockages, or other issues can be managed effectively without disrupting the entire system. Conversely, other terms may refer to specific types of valves with distinct functions: a service valve is usually found at individual fixtures for local control, a riser valve pertains to vertical pipe systems, and a zone valve is utilized to regulate flow in specific areas or zones of a plumbing system. Thus, the correct term for the shutoff function in the main supply line is indeed "Main Line Valve."