Legionella

Citation

(1998), "Legionella", Facilities, Vol. 16 No. 3/4. https://doi.org/10.1108/f.1998.06916cab.006

Legionella

Legionella

For facilities managers of hotels. schools, offices, leisure and sports facilities up and down the country, the liquid problem that is uppermost in their minds has nothing to do with accounts books but everything to do with the extra "guests" and "team-mates" who will not be signing the register ­ Legionella.

Facilities managers will be aware, via health and safety executive literature, that Legionella can be halted in its deadly tracks by keeping cold water at less than 20°C and storing hot water at a temperature of 60°C. What they also know. but mercifully not from experience, is that water stored at 60°C and delivered to the tap or shower-head at 50°C poses a very serious threat of scalding ­ a dangerous dilemma indeed.

HSE guidelines recommend fitting thermostatically-controlled valves, whereby water can be blended at point of use down to 43°C to prevent this risk of scalding. Yet the facilities manager who reads further afield may find, to his or her dismay, that: "while temperature remains the main method of (bacteriological) control advocated in HS (G) 70, there remains doubt about its effectiveness ..." (Nigel Pavey, Senior Research Engineer, Building Services Research and Information Association).

Disinfection with hypochlorite is an often-tried next option, but has its own inherent problems. Traditional fill-and-soak disinfection methods use huge and expensive volumes of water and may be disruptive to the normal use of a building. It is obviously, not desirable (or cost-effective) to close a hotel or leisure centre while "Legionella-control" is carried out.

More importantly, fill-and-soak methods have often failed to eliminate Legionella from hospital water systems, principally because chlorine has only limited value in eradicating biofilms from the water. Biofilms form in tanks and pipes to provide an ideal environment for bacteria to lodge and proliferate, and water authorities have long recognized that Legionella pneumophila can colonize biofilms with potentially deadly results.

At this point, facilities managers are probably ready to drown themselves in the wretched water and leave the problem to someone else. Enter Purogene ­ a unique formula of stabilized chlorine dioxide with proven benefits of continuous bacteriological control of water systems where other methods are ineffective.

Purogene can be used either in continuous dosing of hot water systems or via occasional online disinfection. Continuous dosing means continuous control of biofilms and therefore legionella at a scald-free water temperature of 43°C. There are no point-of-use mixer valves to install and maintain, and no annual fill-and-soak disruption to the building's normal operation.

Where continuous treatment is not required, Purogene is equally effective when introduced into the water system via the unique online portable disinfection system unit. The PDS delivers Purogene to the water storage tank at drinking water inspectorate-approved levels with no water system shutdown or water wastage, the PDS can be easily disconnected and moved to another building if required.

Whichever method of Purogene treatment is used for water quality management, there are additional benefits which include no premium for night or weekend work. No risk to building occupants, due to the high levels of disinfectant normally used in the water, and continuous control of other micro-organisms, which may cause problems for the health of the occupiers and/or the water system itself.

Purogene's properties have long been proven in use in hospitals and care homes ­ where patients and residents are especially vulnerable to infection. In the healthcare market, where resources are also at a premium, Purogene's cost-effectiveness has also contributed to its success. Its versatility means it is suitable for use in any environment where water quality management is a priority ­ from schools to hotels, sports centres to offices.

J.S. Colbourne (Thames Water Authority Laboratories) (1987) P.J. Dennis (Public Health Laboratory Service, Porton Down).

Further information from: Gill Bateman, Vernagene, Folds Road, Bolton BL1 2TX. Tel: 01204 529494; Fax: 01204 521862.