SUSTAINABLE ENVIRONMENT
AND THE FUTURE OF WATER TREATMENT IN THE UK
LEGIONELLA CONTROL E
very year in the UK, there are between 300 and 400 reported cases of Legionnaires’ disease, a form of pneumonia brought on by the inhalation of Legionella bacteria. Older people and those with underlying health conditions are most at risk of being infected, which means the disease can often prove fatal. Whilst larger outbreaks of Legionnaires’ disease are generally
associated with cooling towers, the more frequent smaller outbreaks and individual cases are usually attributed to hot water distribution systems. In recent years, there has been evidence that Legionella is not the only danger from contaminated hot water systems, but that Pseudomonas aeruginosa can also pose a risk, if it is not kept within control limits. Large buildings often contain central hot water storage with extensive, sprawling pipework, providing ideal
breeding grounds for bacteria. Because of this, non-domestic premises such as universities, hospitals, schools, health clubs, leisure centres and hotels require alternative measures to minimise the risk. Recent outbreaks of Legionnaires’ in UK healthcare facilities serve as stark reminders for all those involved with the maintenance of public buildings of how seriously water treatment must be taken.
What is Legionella?
Legionella species are widespread in the environment and can be found living in small quantities in the fresh water of lakes and rivers. They can also be found in man-made water reservoirs such as hot and cold water systems, cooling towers and other water storage systems. There are dozens of different species of Legionella bacteria, but it is Legionella pneumophila serogroup 1 that accounts for most of the reported Legionnaires’ disease cases. The requirements for the growth of these bacteria include temperatures between 25°C and 42°C as well as the presence of nutrients. The occurrence of scale, sediments, organic matter and rust makes pipes the ideal environment for the bacteria to thrive, whilst water stagnation due to low water demand sustains the formation of biofilms, where Legionella can persist. If the appropriate treatment measures aren’t in place, contamination can also occur when water is in transit, storage, or via backflow from non-potable water systems.
Understanding the responsibilities
The UK Water Supply Regulation, 1999 requires that the property owners and facilities managers are held responsible for maintaining the water quality in non domestic buildings. Under Health and Safety Law, they have the legal duty to safeguard a building’s water users from contracting any disease by identifying sources of risk, managing and controlling the risks, and keeping records of
22 PSS MAGAZINE • NOVEMBER/DECEMBER 2015
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