Legionella: What you need to know | Testo Limited Blog

Recently there have been a number of (what should have have been) fairly high profile incidents of Legionella throughout the country. Recently there have been serious cases in Scotland, the Wirral and Surrey, so given that this is clearly an issue which could affect you regardless of where in the UK you live, it should be concerning that more exposure and coverage is not given to the issue to ensure that people know what they need to.

Named after a mysterious outbreak at a convention of the American Legion in 1976 (which affected 221 people) the pathogenic Legionella bacterium is most commonly found in water systems. The Legionella bacterium thrives in warm, moist areas and as such it manages to find ideal breeding environments in areas including cooling towers of air conditioning units for large buildings, hot water systems and spas.


Different variants of the Legionella bacterium can have different effects on humans including strains which can cause either Pontiac fever or Legionnaires disease. Both of these are can be serious conditions and are characterised by symptoms such as fever, chills, muscular aches, coughing and the production of sputum. In very serious cases these illnesses can even lead to death.

Obviously then, these are illnesses best avoided and in order to do so there are 2 major contributing factors which need to be carefully monitored and controlled. These two critical factors are temperature and hygiene of the water within the system in question. In order to reduce the risk of Legionella bacteria developing in a water system, the purity and integrity of the water should be maintained at all times. Additionally, the temperature of the water should be kept either below 20°c or above 60°c – the range between these temperatures is where bacteria is best able to reproduce. Greater awareness of these two factors should lead to a greater ability to control and manage them and in turn reduce the dangers posed by Legionella.

There are a variety of measurement instruments available (such as data loggers and thermometers) which make this task of monitoring and implementing controls to manage the danger of these bacteria, a relatively simple one. It is largely a lack of information and awareness which causes the neglect of proper care for water systems and which in turn can cause potentially fatal risks. So while you need not panic, if you are involved in the running of a building, business or organisation which has a water system as part of its facilities, Legionella is something which you need to be aware of and which you easily take control of.

For more info on Legionella and Legionnaires disease see the HSE website.