Legionella

Legionella can survive in the environment (for example, freshwater ponds) and in engineered water systems, with common sources including domestic hot water systems, cooling water systems and swimming pools.  Legionella can survive in water between 6 and 60°C but thrives in water ranging from 20 to 45°C; it is possible for the bacteria to lie dormant in lower temperatures and become active once a more suitable water temperature is reached.  The bacteria are transmitted in airborne water droplets which, when inhaled can potentially cause disease.   There are, on average, 350 cases of Legionnaires' Disease reported in England and Wales every year of which around 8 to 12% are fatal.  Although most healthy people are not at risk from the disease, people over 45 (particularly men) that smoke, are alcoholics, have heart disease or conditions that suppress their immune system are more susceptible.  The disease can involve symptoms such as headaches, fever and respiratory problems and in some cases include vomiting and deliriousness.  However it can also present with nothing more than flu-like symptoms.

It is essential to implement an effective Legionella control program; to monitor and control the bacteria and therefore prevent an outbreak of the disease.  Unfortunately, the water systems in which Legionella can survive are extremely common, present in almost all commercial and residential buildings – including hospitals, care homes and offices.

Hot and cold water systems and water storage pose a real threat in the control of Legionella, and you do not have to look very hard to see why.  Outlets such as showers, baths and spas run between the optimal temperatures for Legionella (20 to 45°C), showers produce aerosol and little used outlets can contain stagnant water – all of which are potential threats in the control of Legionellosis.  Poor management and ineffective cleaning of water systems result in a build up of biofilms, scale and slime, which provide the bacteria with a source of nutrients in which to multiply.    

Recent Legionnaires' Disease outbreaks have been traced back to cooling towers which are very high risk, so much so that your local council must be notified should your company have a cooling tower.  Cooling towers deal with water within the 20 to 45° range and produce aerosols so it is essential that a control program is in place.

Fortunately, Legionella is relatively simple to control with regular services:

- Risk assessments will identify all potential threats and recommend remedial actions
- Samples taken from outlets allow bacteria levels to be monitored
- Monitoring the temperature of outlets ensures the correct range
- De-scaling and disinfection of shower heads and similar will limit bacteria growth
- Flushing little used outlets to avoid stagnating water
- Cleaning and disinfecting water tanks to kill existing bacteria and prevent proliferation

As well as a moral obligation to limit the threat of Legionellosis in your company, there is also a legislative requirement.  Look at our links page for further information.