No, water is not required to be discharged every year during the annual fire pump flow test. NFPA 25 permits closed-loop flow testing every 2 out of 3 years. On the 3rd year, annual flow testing must be performed by discharging water via hose streams or to a drain or suction reservoir. In order to perform closed-loop testing, the fire pump must be equipped with a bypass that returns water to the pump suction, a means to isolate the bypass loop, and a flowmeter in the bypass loop.

Closed-loop fire pump flow testing is beneficial, as it reduces the cost of testing and minimizes water waste. In addition, closed-loop fire pump flow testing limits the disruption associated with flowing large volumes of water, saves time associated with setting up the test, and eliminates some coordination and planning concerns, such as freezing weather conditions.