Insights: Water Hygiene and Testing
What are the risks associated with Legionella?

According to the Health and Safety Executive, if you are an employer, or someone in control of premises, including landlords, you must understand the health risks associated with Legionella.

You are responsible for health and safety and therefore you need to take the right precautions to reduce the risks of exposure to Legionella, including the identification and assessment of the sources of risk, management, prevention, or control of any risks, as well as keeping and maintaining the correct records.

The collective name given to the pneumonia-like illness caused by Legionella bacteria is Legionellosis and it includes the most serious Legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia, and everyone is susceptible to infection. Legionella cannot be caught by drinking contaminated water. To be harmful, the bacteria need to be inhaled. So, while the risk of contracting the Legionella bacteria is rare, some people are at higher risk, such as those who are over 50 years, smokers, or those with underlying health conditions.

The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. Since Legionella bacteria are widespread in the environment, they may also contaminate and grow in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and whirlpool spas.

Legionella prevention and management

As a person responsible for managing risks, you need to understand your water systems, the equipment associated with the system such as pumps, heat exchangers, etc. and its constituent parts. You need to identify whether they are likely to create a risk from exposure to Legionella, and whether:

  • The water temperature in all or some parts of the system is between 20–50 °C
  • Water is stored or re-circulated as part of your system
  • There are sources of nutrients such as rust, sludge, scale, organic matter, and biofilms
  • The conditions are likely to encourage bacteria to multiply
  • It is possible for water droplets to be produced and, if so, whether they can be dispersed over a wide area, eg. showers and aerosols from cooling towers
  • It is likely that any of your employees, residents, visitors etc are more susceptible to infection due to age, illness, a weakened immune system etc and whether they could be exposed to any contaminated water droplets

Any water system that has the right environmental conditions could potentially be a source for Legionella bacteria growth, and in particular, poor maintenance or poor management of a water system can create the conditions for Legionella to thrive.  To manage the risk, you must appoint someone competent to help you meet your health and safety duties and to take responsibility for controlling any identified risk from exposure to Legionella bacteria. A competent person, often known as the responsible person, is someone with sufficient authority, competence, necessary skills, knowledge of the system, and experience. The provider should be someone you would be satisfied with that they can do the work to the standard that you require.

At Compliance Group we provide a unique service to commercial and industrial organisations, government and public bodies and we are recognised experts in Legionella risk management and water hygiene. Our capabilities include Legionella risk assessments and compliance audits, monitoring and control, water sampling and testing and private water supply risk assessments. For more information on our services contact our expert team at

A nationwide

network of intelligent
compliance services.

Network map


Alternatively, please use the form below to leave a message
All Services
Electrical Safety & Testing
  • Fixed Wire Testing
  • Repairs & Installation
  • Emergency Lighting
  • Thermographic Imaging
  • Portable Appliance Testing
  • Electrical Maintenance
  • Lightning Protection
Fire Safety & Protection
  • Fire Risk Assessment
  • Fire Alarm Design, Installation, Certification & Maintenance
  • Fire Extinguishers
  • Passive Fire Protection
  • Fire Suppression
  • Emergency Lighting
Water Hygiene & Testing
  • Legionella Risk Assessment
  • Legionella Compliance Audits
  • Water Monitoring & Control
  • Private Water Supply Risk Assessment
  • Private Water Supply Risk
We use cookies on our website to ensure you get the best experience. By clicking “Accept”, you consent to the use of ALL the cookies. To find out why we use cookies see our Privacy Policy.

Offline Mode

Some media and features may be missing.