What happens to the RV if there is a drop in supply pressure?

When there is a drop in supply pressure, the relief valve (RV) opens to dump the zone. This action is a critical safety feature designed to protect the system from potential backflow or contamination. The relief valve is intended to release excess pressure or allow the discharge of water when the pressure in the supply line falls below a certain threshold.

If the supply pressure drops significantly, without the relief valve opening, there could be a risk of back siphonage or backflow, which could lead to contamination of the potable water supply. By opening, the RV ensures that any potential backflow is mitigated, allowing the water from the affected zone to be discharged and preventing harmful substances from entering the primary water supply. This response is essential for maintaining water quality and ensuring that the plumbing system operates safely and effectively.