Legionella

Legionella risk assessment is required under HSG274 (UK), ASHRAE 188 (US), and equivalent standards in most developed markets. High-risk building systems include: cooling towers (monthly testing required), hot water storage (maintain >60°C), domestic hot water distribution (deliver >50°C at outlets within 1 minute), dead legs in pipework, decorative fountains, and spa pools. Control measures: thermal disinfection (heat to 70°C for 2 hours quarterly), chemical treatment (chlorine dioxide or copper-silver ionisation), temperature monitoring (weekly), and flushing of low-use outlets. Water sampling and laboratory testing (culture method ISO 11731, results in 10-14 days) should be conducted quarterly for cooling towers and annually for domestic systems.

Legionnaires' disease has a 5-10% fatality rate in healthy individuals and up to 25% in immunocompromised patients. Building owners and facility managers have a duty of care to manage Legionella risk. Insurance claims and legal liability following an outbreak can be devastating. Regular testing and documented risk management are essential.