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Why a Legionella risk assessment is key to industrial water safety

By: Jon Greaves on Oct 30, 2018

If you are an employer, landlord or premises manager then you need to be aware of the health risks associated with Legionella and of your legal responsibilities in assessing, identifying and managing that risk.

This blog post explores the key features and risks of Legionella, the potential impact of Legionella bacterium on industrial water systems and the steps to take to ensure that your company is compliant.

What is Legionella?

The Legionella pneumophila bacterium is commonly found in natural water sources such as reservoirs, rivers, hot springs and lakes. In these types of environments however, it tends to exist in relatively low numbers so it is rare for the conditions to be sufficient to present a risk to humans.

Where there is much greater threat to human health is when the Legionella bacterium makes it way into commercial or purpose-built water systems such as cooling towers, spa pools or evaporative condensers, even domestic water hot and cold systems and especially showers.

Legionella thrives in environments where:

  • Water is maintained at a temperature that is conducive to bacterial growth (between the range of 20C and 45C)
  • Breathable water droplets are created and dispersed via wash, spray, showers, cooling towers etc
  • Water is stored or recirculated as part of the water system
  • There is a ready source of nutrients for the bacterium to feed on in the form of sludge, biofilms, corrosion or scale
  • Pre-treated water is drawn from bore-holes or there are potential sources of contaminated water on-site

What are the potential health impacts of Legionella?

The collective term for the group of diseases that are caused by Legionella bacterium is Legionellosis.

Legionella Pneumophilia is the most common bacteria to cause Legionnaires’ disease in people (95% of all cases) which presents as a potentially fatal form of pneumonia and which is especially harmful to people with chronic respiratory, heart or lung conditions or anyone with a compromised immune system.

Symptoms of Legionnaires Disease are similar to those of the flu: including raised body temperature, headache, fever, muscle pains and cough. Cases can vary in severity from mild illness to pneumonia - and in worst cases to respiratory failure or multi-organ failure.

Similar, but significantly less harmful, conditions also caused by the Legionella bacterium include Lochgoilhead Fever (named after a UK outbreak caused by Legionella micdadei in 1988) and Pontiac Fever (named after the city in Michigan where the first US case was identified.)

Legionella-related diseases rarely spread person-to-person but are acquired via the inhalation of contaminated water droplets.

Public Health England (PHE) conducts a national surveillance scheme for Legionnaires Disease in England and Wales, with the aim of detecting clusters and outbreaks of Legionella, identifying sources of infection and suggesting methods for the control and prevention of future cases.

Legionnaires Disease is RIDDOR reportable.

Who is responsible for Legionella testing?

Any company in the UK with five or more employees is required to carry out a risk assessment and then to  record of any significant findings, retain the results of any inspections, checks or tests for a minimum of five years.

Carrying out a Legionella Risk Assessment is something you can choose to take on within your own organisation as long as there is someone who is competent to do so. Or you may prefer to call in the expertise of a water treatment and hygiene specialist who will be able to provide you with a formal independent assessment of your on-site assets, risks and recommended actions.

Legionella Risk Assessment updates are required to be always up to date and need to track significant changes in the water system including changes to control, dosing, softeners etc and or if Legionella is detected. For more guidance, please contact us.  

How can you prevent and control Legionella?

The Health and Safety At Work Work Act 1974 (HSWA) requires there to be appropriate risk assessments. 

A broad framework is also laid out in the Management of Health and Safety at Work Regulations (MHSWR) while more specific actions are outlined in the Control of Substances Hazardous to Health Regulations 2002 (COSHH).

The Approved Code of Practice: Legionnaires Disease (ACoP L8) provides practical advice on the steps to take to manage and control Legionella risk in your environment, which include:

  • Ensuring the proper control of release of water spray
  • Avoiding water temperatures or conditions that support the growth of Legionella
  • Eliminating the use of any materials that may encourage the growth of Legionella
  • Treating water to limit the growth of Legionella
  • Keeping pipe lengths short to avoid stagnation of water 
  • Maintaining records of control measures, repairs and maintenance

Given the right combination of environmental conditions, Legionella has the potential to thrive in any water system - and if left unchecked, it presents a formidable threat to human health.

The prevention and control of Legionella bacterium is an essential responsibility for all companies in ensuring that your industrial water system, and the water within it, maintains the highest levels of safety and compliance.

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Topics: Legionella Control

Jon Greaves

Written by Jon Greaves

Jon has progressively worked through operational roles, account management, technical management, and senior management roles over the last 16 years within one of the group companies before moving into the role of Water and Air Managing Director. Jon has experience across multiple sectors of water and air compliance, including district energy networks; data centres; healthcare; food and beverage and facilities management. Jon acted as a corresponding steering committee member on CIBSE CP1 – Heat Networks Code of Practice for the UK released in 2020.

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