Control of Legionella spp in the water supply systems of mass accommodation facilities

Legionella Pneumophila is the most common but also the most dangerous strain of the Legionella spp family. This is the cause of Legionnaires' disease, which is a severe form of pneumonia. Transmission to humans occurs through the inhalation of microscopic water droplets (aerosols). The disease has a mortality of about 5–10%, and people with underlying diseases, the immunocompromised, smokers, and the elderly are at higher risk. Control of Legionella spp in water systems.

Legionella growth can be observed
• In water at temperatures between 20°C and 50°C
• In pipes with little or no water flow (including unoccupied rooms)
• On scale deposits and corrosion in pipes, showers and taps
• In water heaters and hot water tanks
• In hot and cold water cisterns and tanks
• In rubber fibers and natural fibers in anti-friction rings and sealing devices
• On sediments/sludge (biofilms) and dirt on internal surfaces of piping and tanks.

The reduced flow or stagnation of water combined with the environmental temperatures in the water supply systems and the faulty maintenance of mechanical equipment during the period of partial or total shutdown of a building, may create favorable conditions for the growth of Legionella Pneumophila in their water systems.

Possible foci of infection

Within the places of mass hospitality the most common places where Legionella grows are:
• Cold-hot water supply systems (shower)
• Air conditioning cooling towers
• Water storage tanks
• Hot springs
• Thermal springs
• Swimming pools (especially those that
are heated)
• Fountains
• Humidifiers and respirators that work with tap water.

Prevention & control actions

• Keep the hot water at a constant temperature between 50°C – 60°C
• Keep cold water consistently cold and below 20°C throughout the system and to all outlets
• Keep shower heads and faucets clean and free of scale
• Regularly clean and disinfect cooling towers and associated piping used in air conditioning systems – at least twice a year.
• Regularly clean and disinfect the tanks and all water filters, according to the manufacturer's instructions
• Implement a Legionella control program especially after a period of standing water and restarting seasonal units

Legal limits & control frequency: According to Γ1(d)/G.67322/6.9.2017 Health Regulation - K.Y.A. (Government Gazette 3282/B/19.9
.2017) the presence of Legionella must be tested every 6 months and its limit is 1000cfu/L.

Corrective actions
If Legionella is detected you should
to do
• Thermal disinfection (direct energy but
quite energy intensive)
• Chemical disinfection (usually by application
chlorine)

Control of Legionella spp in water systems

Tsakalidis Analysis & Testing laboratories have been supporting professionals in the hospitality industry for many years. With our many years of experience in the detection and treatment of Legionella, we are at your disposal, to serve you and guide you in the effective protection of your space in order to ensure a healthy environment for your customers.

For any additional information you can find us
Tsamadou 12, 185 31 Piraeus l tel.: +30 210 4175865
e-mail: sales@tsakalidislabs.gr website: www.tsakalidislabs.gr