Legionnaire's Disease: A risk Assessment of your Property

From time to time reports surface in the news about a new outbreak of legionnaire's disease. The reports normally follow a pattern. They tell of people being taken ill at a public place, such as at a swimming pool or in an air conditioned building, and of investigators having identified high concentrations of the legionella bacteria in the property's water system as being the cause. In the most severe cases the outbreak becomes fatal, lives being lost as a result of the property owner not taking sufficient precautions to assess and control the risk. But what is less well publicised is the fact that the legionella bacteria is often present in all natural and manmade water systems, domestic hot and cold water systems included. In small concentrations the bacteria is harmless. Let it accumulate though and you could find yourself dealing with an outbreak of legionnaire's disease in your own home!

What is legionnaire's disease?

Named after a severe outbreak of illness at a meeting of the American Legion in 1976, legionnaire's disease is a potentially lethal form of pneumonia. It is caused by the inhalation of water droplets / moisture from water sources containing high amounts of the legionella bacteria. Not everyone who inhales moisture laden with the bacteria contracts the disease. Fit and healthy people with strong immune systems, especially those younger than 20 years of age, are very unlikely to have a problem. Males over the age of 45 are most at risk. If the victim is a smoker and/or a heavy drinker, or if the person exposed to the bacteria suffers from respiratory illnesses or has an impaired immune system, the chances of catching legionnaire's disease is that much higher.

The symptoms

Self-diagnosis of legionnaire's disease is not easy. The symptoms are very similar to common flu. Look out for…

• Fever and high temperature
• Chills
• Muscle pains
• Cough
• Diarrhoea
• Pneumonia
• Mental confusion

The easiest way to determine if you have legionnaire's disease is to visit your doctor. They can prescribe a test to help identify the disease. If the disease is circulating in your community your doctor will be aware of this too - a factor that could aid in your diagnosis.

Legionnaire risk assessment and solutions

Legionnaire's disease is caught only from water sources containing high levels of the legionella bacteria. A build up of the bacteria happens over time in water that stagnates. Optimum conditions for development are when the temperature of the water is consistently between 20°c and 45°c, and where there is rust, sludge or organic material present in the system. Very quickly, over a matter of months, legionella can multiply to a dangerously high concentration.

While it is true that blocks of flats, office buildings and other large-scale premises, where water has a greater opportunity to stagnate, are most at risk of harbouring the legionella bacteria, on rare occasions it can be problematic in residential property. The question you have to ask yourself then is are you and your family at risk in your own home? If the domestic hot and cold water systems are in almost constant use it is unlikely that the water will remain stagnant enough for the bacteria really to get any sort of a foothold. However, if there are baths, showers and taps in rooms that are rarely used there is an opportunity for the bacteria to grow in the pipes where the water is not moving. If you leave your home unoccupied for several months, again there is a risk that the bacteria could build up in your water system. Redundant pipe work (deadlegs), such as a pipe to a washing machine that is no longer in use, is another environment for the bacteria to grow - especially if there is debris in the system, this being the bacteria's 'food'.

So what should you do if you think that your water system is at risk? Well, unfortunately, there's no alarm system available yet to alert you to a build up of the bacteria. It's therefore down to you to take preventative action. First, consider regularly flushing your water system through - i.e. open all taps and water outlets and let the water run for a few minutes. Also, look to remove any redundant pipe work and clean the system so it is free from debris. Replacing old steel and lead pipes with modern copper alternatives can help reduce the risk too, as can regularly bleeding your radiators. Another precautionary measure is to periodically increase the temperature of your hot water tank to 60°c or above for a few days at a time: the bacteria is unable to survive in water above this temperature. Finally, if you are worried that your water system is already infected, you can use a chlorine disinfectant to cleanse it. Should you opt for this course of action do flush the system through thoroughly before recommencing normal use.

Renting your home?

In a recent change to government legislation providers of residential accommodation are now fully responsible for protecting their tenants from exposure to legionnaire's disease, just as commercial premises are. By law, to control legionella, you are required to carry out a risk assessment of your premises and introduce measures to control risk where it is found. For more information on how to implement risk assessment and control measures you should contact the Health and Safety Executive or visit their website at www.hse.gov.uk