Legionellosis is the term for infections caused by Legionalla Pnuemophila with the best known illness being Legionnaires Disease. This is a type of pneumonia that principally affects people that are susceptible due to age, illness, immuno-supression, smoking and can be fatal. The bacteria can also cause less serious illnesses which are not fatal or permanently debilitating, but which can affect all people.
Premises are at risk include:
- water systems incorporating a cooling tower
- water systems incorporating an evaporative condenser
- hot water services where the volume of hot water and the system does not exceed 300 litres
- hot and cold water services irrespective of size in premises where occupants are particularly susceptible,
- humidifiers and air washers which create a spray of water droplets and in which the water temperature is likely to exceed 20oC
- spa pools and baths in which warm water is deliberately agitated and recirculated
- other systems containing water which is likely to exceed 20oC and that can release a spray or aerosol during normal operation or when being maintained may also present a risk for example showers.
Legal requirements
The Control of Substances Hazardous to Health Regulations 2002 (COSHH) relates to the risks from hazardous micro-organisms, including Legionella and chemicals such as biocides and chlorine. Under these Regulations risk Assessments and the adoption of appropriate precautions are required to be made.
The Approved Code of Practice and Guidance - The Control of Legionella Bacteria in Water Systems sets out further statutory requirements for dealing with this risk. It applies whenever water is stored and used in a way which may create a reasonably foreseeable risk of Legionellosis and in particular to the plant and systems whenever the Health and Safety at Work Etc act 1974 applies. The Code of Practice places responsibility on employers and persons responsible for buildings and processes to carry out a risk Assessment:
The risk Assessment should take account of:
- the potential for droplet formation
- the water temperature
- the likely risk to those who will inhale the droplets
- the means of preventing or controlling the risk
- Prepare a Scheme for Preventing or Controlling the Risk The primary objective should be to avoid conditions which permit Legionella to proliferate and to avoid creating a spray or aerosol.
This can be achieved by:
- Avoiding water temperatures between 20oC and 45oC. Water temperature is a particularly important factor in the control of the risk.
- Avoiding water stagnation. Stagnation may encourage the growth of biofilm that can harbour Legionella and provide local conditions that encourage its growth. If water is allowed to stand for long periods in warm buildings or in hot weather its temperature is more likely to rise above 20oC.
- Keeping the system clean so as to avoid the build-up of sediments etc. which may harbour bacteria or provide a nutrient source for them.
- An adequate water treatment regime .
- Ensuring that the system operates safety and correctly and is well maintained.
- Keeping records of the precautions implemented.
In addition to prevent or minimise the multiplication and dissemination of Legionella you should:
- control the release of water spray
- avoid water temperatures and conditions that favour the growth of Legionella and other micro-organisms
- avoid water stagnation, e.g. by keeping pipe lengths as short as possible
- avoid the use of materials that harbour Legionella and other micro-organisms, or provide nutrients for their growth
- maintain the cleanliness of the system and the water in it
- use water treatment techniques which either kill Legionella (and other micro-organisms) or limit their ability to grow
- take action to ensure the correct and safe operation and maintenance of the water system and plant.
Cooling Tower Notification
All premises where cooling towers and evaporative condensers are situated must registser with the Local Authority. The prime purpose of this is to identify potential areas that could give rise to spread of infectious disease e.g. legionella and to ensure preventative measures are taken to eliminate the risk of such infection arising to employees and the public.
Spa Pools
Spa pools (also known as hot tubs, whirlpool spa, whirlpools and commonly as Jacuzzi™ which is the name of one particular brand) can offer a pleasant relaxing environment for a few people to sit in together and enjoy the effects of the air and water jets.
However the water is not replaced after each use but disinfected and recirculated. If they are not managed properly spa pools can be the cause of infections. The most severe is the potentially fatal Legionnaires' disease which has even been caused when the spa pools were simply on display for sales purposes. As a recognised source of Legionnaires' disease they are subject to health and safety laws requiring managers, designers, manufacturers and installers to ensure spa pools remain safe.
Whirlpool baths are similar to spa pools but are normally only used by one or two people at a time, are often found in bathrooms and are drained after each use but they are still a potential source of infections if not looked after properly.
The Health Protection Agency has produced guidance that will be of use to all who have anything to do with spa pools from the designer to the user. Following this guidance will normally ensure compliance with the law.
Part 1 details the legal duties of owners, managers, designers, manufacturers, importers, suppliers and installers and Part 2 provides practical guidance on the control of infectious agents in spa pools encompassing: treatment programmes; monitoring; cleaning and disinfection; design and construction; whirlpool baths; and hiring and other commercial uses. It also includes checklists to assist with auditing risk Assessments; a trouble shooting guide; poolside water testing procedures; a list of sources of information and a comprehensive index.