Legionella Risk Assessment of Novel Water Systems

Current legislation and guidance relating to the control of Legionellosis in water systems concentrates primarily on the most common water systems, cooling systems and domestic hot and cold water systems.

There are however, many other water systems that have the potential to allow the proliferation of legionella bacteria that may then give rise to an outbreak of Legionnaires' disease and such water systems should therefore be reviewed as part of any legionella risk assessment process.

However, because of the "novel" nature and complexity of such water systems it is our experience that many water treatment and water hygiene service providers offering legionella risk management services often fail to evaluate the risks posed by such systems correctly or miss them from site evaluations and legionella risk assessments.

However, current guidance from the Health & Safety Executive, together with BS 8580:2010 "Water quality - Risk assessments for Legionella control - Code of practice" make it clear that any water system that operates in the legionella temperature growth zone (20oC to 45oC) and which may produce a breathable aerosol has the potential to cause Legionellosis and should therefore be considered a risk, and as such should be assessed.

Other Water Systems

Novel and other water systems that may present a legionella risk include:

  • Fire suppression systems
  • Fountains and water features
  • Humidifiers, ultrasonic, spray and steam
  • Vehicle wash systems
  • Tunnel washers
  • Air scrubbers
  • New technologies
  • Water saving devices
  • Water harvesting systems for rainwater and greywater
  • Solar heating
  • Ground, air and water source heating
  • More...

Legionella Risk Assessment

In the absence of any specific guidance for a given “novel” or other water system it is important to consider the causal chain for Legionnaires' disease as clearly detailed in BS8580:2010 and perform a more holistic appraisal of the system under scrutiny.

Only when an experienced legionella risk assessor takes this approach can an accurate assessment of the risks involved be arrived at.

A similar approach to the derivation of an effective written scheme must also be taken, the current guidance only offers written schemes for evaporative cooling systems along with those for hot and cold water systems.

“Novel” water systems are most common in engineering, manufacturing and process industries and would include installations such as plasma cutters, tunnel washers, cutting machine coolant systems, automotive humidification and paint spray removal systems etc.

Responsible Persons in any of these industries would benefit from discussions with a Legionella Control International consultant who would offer advice and guidance of a bespoke nature.

Expert & Impartial Advice

Legionella Control Internationals teams of experienced legionella risk management specialists offer expert and impartial advice on the prevention and control of exposure to legionella bacteria in all engineered water systems including hot and cold water systems, cooling systems, cooling towers, and complex and novel water systems.

Identification and assessment of the risk

" ... the person who carries out the [legionella] risk assessment and provides advice on the prevention and control of exposure must be competent to do so."

Paragraph 29. Health & Safety Executive Approved Code of Practice and guidance L8 "Legionnaires' disease. The control of legionella bacteria in water systems"

In the United Kingdom we are members of the Legionella Control Association (LCA) and are accredited by them to perform legionella risk assessments of all system types... LCA registration certificate

Expert Legionella Assistance

For further information and specialist assistance regarding our legionella risk assessment services please call +44 (0) 161 877 0586 to speak to one of our specialists or email your questions to This email address is being protected from spambots. You need JavaScript enabled to view it..

Get in touch...

Legionella Control International
Unit B Badex Building
Westbrook Park
Manchester M17 1AY
United Kingdom

Manchester: +44 (0) 161 877 05 86
London: +44 (0) 203 637 47 48
Email: info@legionellacontrol.com

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