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Legionnaires Disease and Cooling Towers

In order to combat Legionnaires Disease Stratford's Environmental Health Officers are calling on Business's to register their cooling towers. The District Council has a register showing that there are currently twenty two towers registered in nine locations. Owners of premises using wet cooling towers and/or evaporative condensers must notify the District Council that they have this equipment. Notification enables environmental health officers to carry out proactive inspections and provide vital information before an outbreak of Legionnaires' disease occurs.

Notification of Cooling Towers and Evaporative Condensers Regulations 1992

The above legislation requires the notification of:-

a) The installation of cooling towers or evaporative condensers

b) The removal of such equipment

c) Significant changes to towers and condensers to the local authority.

The information contained in the notification is required to help in the investigation and prevention of outbreaks of legionellosis by regulating the use of cooling towers and evaporative condensers. Such equipment may be found in some engineering works and 'wet' air conditioning systems.

In order to ensure that the register of evaporative condensers and cooling towers contains up-to-date information you should complete a notification form if any of the above applies to your installation.

Notification forms are available from the Public Protection team by telephoning 01789 260832 or by emailling envhealth@stratford-dc.gov.uk.

WHAT IS LEGIONNAIRES' DISEASE?

Legionnaires' disease is one of a group of pneumonia-like illnesses collectively known as legionellosis. ost reported cases have been in people aged between 40 and 70; men are more likely to be affected than women.

WHERE IS LEGIONELLA FOUND?

Legionella bacteria are widespread in natural sources of water. They are also found in many recirculating and hot and cold water systems. Outbreaks of legionnaires' disease have occurred in or near large building complexes such as hotels, hospitals, offices and factories.

IF LEGIONELLA IS SO WIDESPREAD WHY AREN'T THERE MORE OUTBREAKS?

Infection is caused by people breathing in water aerosols contaminated with legionella bacteria. For infection to occur a chain of events has to take place and fortunately this happens rarely. The chain includes:

Conditions suited to the multiplication of the organism, i.e. water temperature in the range 20°C to 45°C.
The presence of sludge, scale, rust, algae and organic matter to provide nutrient.
Means of creating an aerosol.
Inhalation of the aerosol by a susceptible person.

Cooling towers, which are wet or evaporative condensers that form part of an air conditioning system, can present a particular hazard because they readily generate fine water droplets and there is an air current to transport them. As they are usually located on rooftops there is a potential for infecting large numbers of people. The bacteria may also colonise hot and cold water systems - showers and spa baths have been associated with infection.

HOW CAN THE RISK BE REDUCED?

Since legionella is widespread in the environment, it cannot be prevented from entering water systems. However, taking the following precautions can reduce the risk of an outbreak developing:

Hot and cold water service

cisterns and pipe work should be designed so that water is not allowed to stand undisturbed for long periods;
cisterns should be well covered to prevent the entry of dirt, debris and vermin, and should be periodically inspected, cleaned and disinfected;
water temperatures between 20°C and 45°C should be avoided by insulation of cold water tanks and pipes in warm spaces, and by storing hot water at 60°C and circulating at 50°C. Where there is a risk of scalding for the very old, and young children, thermostatically controlled taps may be needed;
only water system fittings and materials which comply with water authority by-laws should be used (certain materials, e.g. leather, some rubbers and plastics, support the growth of bacteria and should not be used).

Cooling towers

cooling towers and their associated water systems need to be well designed, maintained and operated; the fitting of efficient drift eliminators which reduce the escape of spray is especially important;

systems should be cleaned and disinfected at least every six months;
water should be treated to prevent scale, corrosion and microbiological growth;
where reasonably practicable, cooling towers should be replaced with dry cooling systems.

Other water systems

Precautions are necessary wherever water conditions are likely to support the growth of bacteria and there is a means of dispersing droplets, e.g. commercial spa baths and humidifiers.

WHAT ARE THE LEGAL DUTIES?

The Health and Safety at Work Act and the Control of Substances Hazardous to Health Regulations both apply. Practical guidance on the legal duties is given in an Approved Code of Practice from the Health and Safety Commission.

For further information please contact the Public Protection team on 01789 260832, or by email at envhealth@stratford-dc.gov.uk

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Stratford-on-Avon District Council
Elizabeth House,
Church Street,
Stratford-upon-Avon,
Warwickshire,
CV37 6HX

E: info@stratford-dc.gov.uk
Tel: 01789 267 575
Fax: 01789 260 007
Minicom: 01789 260 747
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