How is a closed water system created?

A closed water system is created through the strategic installation of a check valve on the water service line, typically located near the house shut-off. A check valve allows water to flow in one direction only. When installed in a water service line, it prevents backflow and maintains the pressure within the system. This means that once the water flows into the system, it cannot re-enter or escape back toward the source, effectively sealing the system and making it 'closed.'

In contrast, a pressure relief valve is used to relieve excess pressure, which does not contribute to creating a closed system but rather serves as a safety feature in scenarios of pressure build-up. Ensuring that all faucets are closed tightly does not guarantee a closed system since there could still be pathways for water to exit or air to enter the system. Similarly, the use of flexible hoses does not create a closed system by itself; they can still allow for leaks or unwanted water movement if not properly secured. Thus, the installation of a check valve is essential in establishing a truly closed water system.