Water Management: Legionnaires Disease

Legionnaire’s disease was first identified in 1976 in the USA and is generally considered to be a disease of the developed world where the water we use in buildings if not looked after properly can provide an ideal environment for the bacteria. Drinking water with this particular bacteria in it will not cause a problem as it needs to be inhaled in small aerosol particles, even windscreen wash bottles have been implicated! The issue of potting compost has also raised its head in the UK although this is probably one of the commonest ways of contracting legionella in Australia (N.B. This form of Legionella is caused by a different species of Legionella bacteria). Although it is still cooling towers that generate large outbreaks (such as that seen in South Wales over this summer), wherever water is stored, conditions are right and aerosols are produced the risk of Legionella infection exists.

Water systems in blocks of flats or even individual flats can provide suitable conditions for Legionella when:

  • Temperatures lie between 20-45ºC;
  • Water is allowed to stagnate in dead-legs and unoccupied premises;
  • There is a source of nutrients – perhaps from a dirty water storage tank/water heater.

In the UK the Health & Safety Executive has published guidance in the form of a document referred to as L8 – The control of legionella bacteria in water systems. This is available as a free download from the HSE website, there is also a summary of the main issues in another guidance document entitled, Essential information for providers of residential accommodation. This again can be downloaded free of charge(www.hse.gov.uk) then follow links to Legionnaire’s diease page.

The first step in ensuring you building/flat meets its legal requirements is to get a Risk Assessment carried out. There will shortly be a specific British Standard published to cover the mechanics of carrying out a suitable assessment. There are plenty of companies who can offer this service and perhaps the first port of call would be the Legionella Control Association’s web site where you will find a list of companies who have met the LCA’s requirements – www.conduct.org.uk.

L8 identifies four factors that are required to create a risk of acquiring legionellosis:

  • the presence of legionella bacteria;
  • conditions suitable for multiplication of the organism e.g. temperatures(20-45ºC) and a source of nutrients e.g. sludge,scale,rust, algae and other organic matter;
  • a means of creating and disseminating breathable droplets e.g. aerosols generated from showers/taps/flushing WC etc.,
  • the presence(and numbers) of people who may be exposed, especially in premises where occupants are particularly vulnerable, e.g. healthcare.

Legionnaire’s disease continues to kill and severely curtail the quality of life or people who survive an attack. The worrying fact is that in almost every case that has been investigated, if simple precautions had been taken subsequent fatalities could have been so easily avoided.

This has led to the HSE successfully prosecuting a number of building owners/individuals when outbreaks have occurred. Company directors, owners and operators of buildings need to understand they have a statutory duty to control the potential risks from Legionella and that failure to do so can result in criminal prosecutions with heavy fines and potential imprisonment.

However please do not throw you hand up in horror at yet another health and safety issue that you need to address – generally the solutions to control Legionella are simple and do not have to cost the earth. There is plenty of help and advice available from the HSE and LCA members. Other consultants like myself who are members of the Water Management Society of the Royal Society of Public Health can also provide unbiased advice on the best methods to control Legionella – remember You are not alone!!

Stuart R Wilton BSc(Hons);MSc;FRSPH;MWMSoc
Air & Water Consultants Limited
07973 891196

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