There are various systems available to supply hot and cold water services that range in size, scale and complexity. All can present foreseeable risk of exposure to legionella.
Before assessing the risks associated with these systems, you need to understand the type of system, its constituent parts and operation. Simplified examples of different basic systems are:
This site will help you to understand what you must do’ for
Larger buildings with more complex hot and cold water systems; and healthcare establishments e.g. NHS premises, hospitals
You should consider the guidance in Legionnaires’disease: The control of Legionella bacteria in water systems which covers the following topics:
In addition to considering information in Legionnaires’ disease: The control of Legionella bacteria in water systems, you will also need to consider relevant NHS guidance in parts A and B of The control of Legionella,hygiene, "safe" hot water, cold water and drinking water systems. This gives comprehensive advice and guidance about the legal requirements, design applications, maintenance and operation of hot and cold water supply, storage and distribution systems in all types of healthcare premises.
Smaller buildings with less complex hot and cold water systems e.g. residential accommodation, care homes, housing associations.
This information is for a wide range of organisations from community halls to care homes to university multi-storey accommodation blocks. As an employer, or someone in control of premises including landlords, you have a responsibility to undertake the duties in ‘what you must do’ to ensure that the risk from exposure to Legionella in your premises is properly controlled. You must undertake a risk assessment and review it if there are significant changes e.g. expansion of water system, changes in resident population.
You will also need to consider the susceptibility of your staff and, particularly those more at risk of infection due to age, illness, infirmity, smokers, alcoholics or a weakened immune system.
Where you are using temperature as your primary control, the following basic information may help you to understand the risks that your water system might present and the action you may need to take to help you make informed management decisions (Hot and cold water systems table). For those wanting full technical details you should consider the guidance in Legionnaires’ disease: The control of Legionella bacteria in water systems.
Where temperature is not used to control Legionella risk there are several alternative methods (part 2 section 168). However, it is important to demonstrate that you are achieving effective control and that other measures e.g. inspection, cleaning, monitoring, recording etc, are undertaken.
There is a risk of scalding where water comes out of taps at temperatures above 44°C. In certain facilities e.g. care homes, this is especially so for whole-body immersion in baths and showers of vulnerable patients, the very young, elderly people, and people with disabilities (who may not be able to recognise high temperatures and respond quickly).
You have a legal duty to assess the risk of scalding and to adopt appropriate measures to control it. Your approach will depend on the needs and capabilities of patients or residents. For capable people, e.g. staff, a warning notice may be sufficient, but if vulnerable people can get access to baths or showers, it is recommended that thermostatic mixing valves be fitted to prevent water being discharged at more than 44°C.
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