Legionella is the name of the bacteria which causes legionellosis, the collective term for the diseases’ the bacteria causes. The most serious of these is Legionnaires’ disease but the bacteria is also responsible for the less serious Pontiac Fever and Lochgoilhead Fever to name but two. It is a gram negative bacteria that is common and can be found in many rivers lakes and streams as well as in man made water systems.

Legionnaires’ disease is a potentially fatal form of pneumonia with certain groups more likely to be at risk. They are: -
- Anyone with impaired lung function
- Anyone with a low immune system
- Over 45s
- and Smokers or heavy drinkers.

The bacteria itself favours specific conditions that will allow it to multiply such as water temperatures between 20 - 45⁰C

The only way to contract the disease is to inhale the bacteria deep into the lungs. It is therefore important to consider how an aerosol can be created within the water systems you have. If it is very likely to happen, linked to the presence or possible presence of people who may fall into the above categories, then you must ensure that you put the necessary control measures in place and that these tasks are carried out.

In the UK we use temperature as the primary means of controlling the bacteria, there are however other methods that can be effective in controlling the numbers of bacteria contained within a water system. Put simply we keep the cold water cold, below 20⁰C and keep the hot water hot, stored at 60⁰C for a minimum of one hour per day and capable of reaching all outlets at 50⁰C within one minute of opening any tap. Obviously keeping systems clean and keeping the water moving help greatly at reducing the risks.

The starting point for achieving control, and then compliance, is to have a legionella risk assessment carried out. A good assessment will give you a list of any areas of non-conformance found, why it is a non-conformance and what you need to do to comply and a full list of the control measures that are required for your site(s).