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Legionnaires Disease and the Notification of Cooling Towers
In order to address the risks from legionnaires disease, regulations exist requiring the owners of cooling towers and evaporative condensers to register the equipment with the local authority. The register maintained under the 'Notification of Cooling Towers and Evaporative Condensers Regulations 1992' is held by the Commercial team in the Environmental Health section.
Notification of Cooling Towers 
Legionnaires Disease
Legionnaires Disease is caused by a bacterium called Legionella Pneumophila. Infection comes about by breathing in a fine spray of airborne water carrying the bacterium. There is no evidence to show that the illness can be caught from someone who has already been infected, nor from drinking water carrying the bacterium.
Those most at risk from infection are smokers, and those already suffering from respiratory illness. However, even healthy people can be infected. Most cases have been in people between the ages of 40 to 70 years, and men are more likely to be affected than women.
The Legionella bacterium is found in natural water supplies and soil, it is also common in re-circulating and hot water systems. Outbreaks have occurred in or near large building complexes such as hotels, hospitals, offices and factories. However, there is no evidence that domestic water systems present any risk.
Reducing the risk of Legionnaires Disease
The Legionella bacterium is widely spread, and it is not practicable to prevent it from getting into water systems, however, the risk of an outbreak can be reduced by following some simple precautions:
Hot and Cold Water Services:
- Tanks and pipe-work should be designed so that water is not allowed to stand undisturbed for long periods.
- Tanks should be well covered to prevent the entry of dust, dirt and vermin, and should be periodically inspected, cleaned and disinfected.
- Water temperatures between 20 c and 45 c should be avoided. Hot water should be stored at 60 c and circulated at 50 c.
- Only water system fittings and materials complying with water authority byelaws should be used.
Cooling Towers
- Cooling towers and their associated water systems need to be well designed, maintained and operated. Fitting drift eliminators, which reduce the escape of spray, is particularly important.
- Systems, and the water in them, should be cleaned and disinfected at least every 6 months.
- Water should be treated to prevent corrosion and the multiplication of bacteria.
- It may be possible to replace wet systems with dry cooling systems.
Other Water Systems
- Precautions are necessary wherever conditions exist that are likely to support the growth of the bacterium and there are means of dispersing water droplets e.g. Spa baths and humidifiers.
What Happens in the Event of an Outbreak
Hospitals and the Health Protection Agency monitor the incidence of Legionnaires Disease so that outbreaks can be quickly identified. As soon as an outbreak is identified a team of specialists mount an investigation to:
- Identify the source.
- Identify the people likely to be affected.
- Ensure that the contaminated water system is treated as quickly as possible.
Contact Details
Should you require any further information or advice about Legionnaires Disease, contact the Commercial Team in the Environmental Health Service via the Customer Service Centre on 01462 474000, at env.health@north-herts.gov.uk or at;
Commercial Team
North Hertfordshire District Council
Council Offices
Gernon Road
Letchworth Garden City
Herts
SG6 3JF
