• The building contains water cooling towers or evaporative condensers
• There are hot water services with volumes exceeding 300 litres
• There are hot or cold-water services, which are particularly susceptible e.g. in hospitals or nursing homes.
• Humidifiers or air washers are used which create water droplets and where the water temperature is 20 degrees C or more.
• Baths / pools or spas where warm water is recirculated.

Note: The COSHH regulations cover hazards from micro-organisms, up to 200 cases of Legionella are reported in England and Wales each year. A professional survey of the equipment/system will usually be required.