Water hygiene

At the Health and Safety Executive's Birmingham legionella conference held in October 2000, details of its recent investigations and future plans on combating legionellosis were revealed. Its new revised Approved Code of Practice and Guidance is now available. A supporting Technical Memorandum from the Chartered Institution of Building Services Engineers, Minimising the risk of Legionnaires' Disease, was published at the same time.

Legionellosis is the name for either of the two diseases created by the water borne legionella bacteria. Legionnaires' Disease is the life threatening pneumonia. Pontiac Fever or a variation of it, Lochgoilhead Fever, is a self limiting form of flu-like illness. The investigative research initiated after the first recognised outbreak of Legionnaires' Disease, which struck 182 members of the American Legion in July 1976, showed that the bacteria was commonplace.

Fortunately the bacteria is readily controlled by ensuring that the water is kept hot or cold or is treated if lukewarm. However, persistent outbreaks were shown to be associated with poorly operating water services, particularly in air-conditioning cooling towers and in hot water systems. Further archival pathogenic investigations showed that the disease was not new.

The Health and Safety Commission produced the first Approved Code of Practice in 1991 (L8), which proposed that a managerial person within every company took on responsibility for water hygiene. The duties for such a person were consistent with Control of Substances Hazardous to Health (COSHH) Regulations (1994). The tasks were to identify the water equipment at the site, take appropriate measurements to assess its temperature, use, cleanliness and residence time and prepare a risk assessment analysis. The actions resulting from this assessment were then prioritised, allowing for the cost and benefit of remedial measures and also for convenience. Records were required and training provided. Specialist organisations provided more specific complementary guidance for their members, particularly the Chartered Institution of Building Services Engineers, and The British Association of Chemical Specialists in conjunction with the Water Management Society.

As Robin Tarry, of the HSE, explained at the conference, in the mid '90s there was an increase in outbreaks associated with evaporative cooling towers in Birmingham, Walsall, Llanelli and Corby. This precipitated a high level of public concern, particularly because many cases are settled out of court and details of the investigations are not readily available to the public. The HSE therefore set up a national programme of inspections from 1997-1999. It wanted to know if compliance was poor or if the guidance was lacking in some way. Over 600 premises containing a cooling tower were visited and an appraisal made on each.

The overall picture was mixed. Compliance was good for the monthly chemical monitoring and six-monthly cleaning of the cooling towers. Around 80 per cent of the towers complied with this. Unfortunately the management of the water was poor. Risk assessment had been done on 69 per cent of towers. Only 64 per cent of companies had nominated a responsible manager for water hygiene and these companies showed a higher compliance than those without such a person. Less than half of the systems were documented. Only 45 per cent of companies had a defined contractual relationship with their water treatment contractor.

The HSE advised 60 per cent of the employers in ways of improving their water care. Formal enforcement action was taken on a third of the premises and a number of prosecutions followed. In 40-50 per cent of cases the inspectors were unable to undertake a complete assessment of the physical condition of the tower. Tighter enforcement is planned and more inspectors are being trained. The Water Management Society is introducing a Code of Conduct to help customers understand what a service company can do. At the moment such a code is voluntary.

Outlining the changes introduced into the new ACOP and Guidance to ensure that service suppliers are effective in both the design and operation of cooling towers, the HSE's Ken Ashley emphasised the need to control, not simply minimise, the multiplication and spread of legionella. The ACOP will be combined with the Guidance details to create a composite document:

• spa pools will be added
  
• the successful temperature control regime to be retained
  
• hot water should always be above 50°C in the re-circulating loops and stored at 60°C
  
• cold water should be below 20°C with the cold water store having a holding capacity of roughly one day's supply
  
• all water should be as clear as practicable to minimise available nutrient
  
• cooling towers are routinely treated with biocide on a continuous basis, and therefore legionella testing to ensure the integrity of the dosing system is recommended quarterly
  
• alternative treatment techniques are encouraged and can be essential whenever the thermal conditions cannot be achieved. Such novel treatments must be monitored closely to ensure that the treatment is effective.

The most critical issue for facility managers is what are the procedures when an outbreak occurs? Roger Watson, director of Environmental Health for Birmingham, recommended that all cooling towers of the evaporative cooling type within the suspected area are closed. This could be critical for some offices.

The lesson for facility managers is to check compliance with the HSC ACOP. Ensure you have a manager formally responsible for water hygiene; know where the water goes within your site (including exterior outlets such as car washes); take the appropriate measurements of temperature, residence time, cleanliness and water treatment recommended in the ACOP; be sure of your contractual relationship with your water treatment specialist if you have a cooling tower; ensure staff are trained; be pleased to show your records to anyone who is interested.