I have recently assumed maintenance responsibility of fire-fighting systems in multi-use buildings with sleeping accommodations. The buildings have standard fire-fighting hose reels fed from the main water supply, which is ambient temperature. These are tested monthly by releasing water through the nozzle to waste. Annually, they are tested by allowing water to flow at full pressure for two to three minutes.
We have fixed and portable water mist fire-fighting equipment. Both systems have pressure of 100-110 bar with droplet size of 70-100 micron. The water storage tank capacity is 250 liters, and the portable systems have a capacity of 25-50 liters.
Is there a definable risk of transmission of Legionella in the use of these systems when fighting a fire or testing the equipment?
No cases of Legionnaires’ disease have ever been reported with respect to aerosols from spraying from hoses. Although aerosolization is considered a mode of transmission for Legionella, in actuality, the major mode of transmission is aspiration associated with drinking contaminated water. I wouldn’t worry about transmission from fire-fighting equipment either during active fire-fighting or maintenance of equipment.