Assessment

Assessing the risk

It should be possible for you to assess the risk yourself, but if you do not feel you have the right skills, you can obtain help and advice from a consultant. When you do the risk assessment, consider the following:

● Are conditions right for the bacteria to multiply, eg is the water temperature between 20oC and 45oC?

● Are there areas where stagnant water occurs (deadlegs), eg pipes to a washing machine that is no longer used?

● Are there infrequently used outlets, eg showers, taps?

● Is there debris in the system, such as rust, sludge or scale (often a problem in old metal cisterns), that could provide food for growing legionella?

● Are there thermostatic mixing valves that set a favourable outlet temperature for legionella growth?

● Are any of your employees, residents, visitors etc vulnerable to infection, eg older people, those already ill?

Answering ‘yes’ to any of these questions suggests there is an increased risk of your residents being exposed to legionella and falling ill.

What should you do if you decide the risks are insignificant?
Review the assessment periodically.

What should you do if you identify risks? 

Introduce proper controls, which could include disinfection of the system - you will need to refer to the ACOP for guidance on the action you should take. As the design, maintenance and operation of the system are crucial in controlling the growth of legionella, any action you take is likely to include the following:

● ensuring water cannot stagnate anywhere in the system, eg remove redundant pipework, run taps/showers in unoccupied rooms;

● keeping water cisterns covered, insulated, clean and free of debris;

● insulating pipework;

● maintaining the correct temperature at the calorifier (ie the hot water cylinder);

● advising maintenance staff working on the system about the risks and how to minimise them; and

● advising tenants about the risks, the control measures you are taking and the precautions they can take, such as flushing through showers following a period of non-use.

Note: raising the temperature of your warm water is one way to control legionella growth, but could also increase the risk of burns and scalding. You will need to consider points like this when you do your risk assessment and decide which control measures to use.

What should you do after assessing the risk and putting controls in place?

Review your risk assessment at regular intervals, especially if any factors change, eg you change your disinfection regime, more vulnerable groups of people (eg the elderly) move into your  accommodation.