Legislation and Compliance

Employers and staff who hold responsibility for the premises (and the people within it) must prepare a written scheme. This is designed to control the risk and prevent Legionella spreading in their systems.

This must on a regular basis, be monitored to ensure it remains effective. Records must be kept of the action taken, so that if there were ever any questions on how your premises controls Legionella, you have evidence to prove you are taking action.

You must carry out a Legionella risk assessment (this is a service offered by Managed Water Services). Appoint a Legionella manager so that they can regularly monitor the systems and can also arrange for work to take place when and if it is needed.

It is important for anyone in your organisation who is responsible to be suitably trained and competent.

On Managed Water Service’s Knowledge Library there is a document called ACOP L8 (this stands for Approved Code of Practice). It is a Health and Safety Commission guidance document which covers the control of legionella bacteria and gives practical advice on how to comply with the law.  If you follow the advice you will be doing enough to comply with the law in respect of controlling legionella bacteria.

The Legionella Risk Assessment should be considered a living document. We would typically recommend it is reviewed every 2 years but a longer period may be appropriate for simple, low-risk systems and a shorter period may be appropriate for those that are more complex. However, if any of the following apply or occur then the assessment must be reviewed: 

  • changes to the water system or its use;
  • changes to the use of the building in which the water system is installed;
  • the availability of new information about risks or control measures;
  • the results of checks indicating that control measures are no longer effective;
  • changes to key personnel;
  • a case of legionnaires’ disease/legionellosis associated with the system.

Legionnaire’s Disease

Legionnaires’ disease is a pneumonia-like disease that has an approximate 12% fatality rate. Symptoms include: Muscle Pains, high temperature fevers and chills, dry cough, headaches that can lead to pneumonia and diarrhoea and signs of mental confusion.

Legionnaires’ disease is caused by Legionella bacterium, a bacterium that occurs in the natural environment.When this bacterium is released in an aerosol, a shower or a spray tap for instance, it spreads out into the atmosphere and can travel a significant distance. If a person comes into contact with the infected aerosol and it is breathed in to the lungs then it can cause Legionnaires’ disease.

In Philadelphia in 1976 a large outbreak of a pneumonia type illness was apparent among people that had attended an American Legion Convention in the city. After sampling of lung tissues an unrecognised bacterium was found and subsequently called “Legionella Pneumophila” and the disease thus called “Legionnaires’ disease.”

Most cases of Legionnaires’ disease are treated in a hospital; however, appropriate antibiotics are an effective way to treat the disease.

According to reports there are approximately 500 cases of Legionnaires’ disease in the UK each year. There are groups of people that are more susceptible than others; Men are more susceptible than women, those over 45 years are more susceptible, those with an underlying illness or addiction will also be more susceptible.

Legionnaires’ disease is diagnosed with a combination of tests, this can include mucus from the patient, a bronchoscopy or a by having a closer look at the lung tissue. Tests can also be used to measure the amount of antibodies in the blood, and also tests using the patient’s urine can measure specific antigens.


Legionella bacterium can also cause Pontiac fever and Lochgolihead fever, both flu like diseases. Pontiac fever has an incubation period of 2-3 days whereas Lochgolihead fever usually has an incubation period of 9 days.

Legionella bacteria are found in natural water environments such as lakes, rivers and reservoirs; however, these are usually in low numbers and so are not dangerous to humans. Legionella bacteria grow under the right conditions: temperatures between 20-45˚C, an available food source e.g. biofilm, rust and algae. Low flow or stagnant water will also help the bacteria grow to large numbers.

Legionella bacteria thrives between 20˚C and 45˚C, they are dormant below 20˚C and are being killed off at 60˚C. Temperature is the primary method of controlling legionella growth in our water systems although other methods using chemicals are also widely used.