New water quality standard coming soon

BS 8580:2010 Water quality – Risk assessments for Legionella control – Code of practice

Legionellosis is an infection caused by bacteria of the genus Legionella. The most serious is Legionnaires’ disease, a severe pneumonia with a relatively high fatality rate, which was first recognized in 1976. Outbreaks and sporadic infections occur throughout the world. At least 50 species of Legionella have been described and 20 have been associated with disease in humans, but the predominant cause of Legionnaires’ disease is L. pneumophila. Legionella spp. are opportunistic pathogens of humans and normally inhabit warm moist or aquatic environments where they grow in association with other organisms.

In particular, they are known to grow in a range of protozoa. Their predilection for warm water means that they are capable of colonizing artificial water systems and equipment containing water. Legionnaires’ disease is not transmitted from person to person, but is of environmental origin and usually contracted by inhaling the organism in an aerosol produced from water contaminated with the organisms. Aspiration of water containing Legionella spp. can also cause infection particularly in hospitalized individuals.

There is a chain of events leading to an individual becoming infected with legionnaires’ disease:

  • The water system needs to become contaminated (inoculated) with the bacteria
  • Conditions have to exist within the system for the amplification of the bacteria to sufficient concentrations to cause infection
  • The contaminated water usually needs to be dispersed into droplets fine enough to form an aerosol for transmission to the victim(s)
  • The victim has to be exposed to contaminated aerosol to inhale it or water to aspirate it
  • The exposed individual has to be susceptible to succumb to infection.

BS 8580 gives recommendations and guidance on the assessment of the risk of legionellosis presented by artificial water systems. It applies to any undertaking involving a work activity or premises controlled in connection with a trade, business or other undertaking where water is used or stored in circumstances that could cause a reasonably foreseeable risk of exposure to legionellae and contracting legionellosis.

The standard applies to risk assessments being undertaken on premises, plant and systems for the first time, and to review and audit where a previous assessment has been undertaken and where control measures might have been implemented.

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