How often should irrigation systems near HVAC equipment be flushed to prevent Legionella growth?

Flushing irrigation systems regularly is crucial to prevent Legionella growth. The frequency of flushing depends on various factors, including water usage, system design, and climate. As a general guideline, irrigation systems should be flushed at least every 3-6 months, or more frequently in areas with high temperatures, humidity, or water stagnation. Flushing should involve running water through the system at a velocity of at least 1.5 meters per second (3.6 feet per second) to remove sediment, debris, and stagnant water that can harbor Legionella bacteria.