What is the primary purpose of a foot valve in a water supply system?

The primary purpose of a foot valve in a water supply system is to prevent backflow. A foot valve is typically installed at the bottom of a pump or well and is designed to maintain the prime in the pump by allowing water to flow into the pump while preventing it from flowing back out. This one-way function effectively stops any potential backflow, ensuring that the water supply is maintained and preventing contamination from outside sources.

In contrast, other options like regulating water pressure, filtering water, or measuring water flow represent different components or functions within a plumbing system and are not the role of a foot valve. For instance, pressure regulators control the water pressure in a system, filters are used to remove impurities from water, and flow meters are employed to quantify the volume of water passing through a system. Each component serves a specific purpose, but in the case of a foot valve, its sole function revolves around preventing backflow, which is vital for the integrity and safety of the water supply.