Are Your Employees Safe From Legionella?

02-October-2018 11:58
in General
by Admin

Legionella is a type of pathogenic bacteria (basically bacteria that leads to infection) that causes a range of pneumonia-like illnesses such as Legionellosis and Legionnaires’ disease. This happens when small droplets of water that contain the legionella bacteria are inhaled, often through water sprays or mists. There is a risk that your water systems may have this bacteria in the water, causing great potentially fatal hazard to your employees.

At the moment you can’t get specific certificates or registers to prove Legionella safety. But it’s important you understand the risks and put measures in place to control them.

This guide provides you with some practical advice on how to fulfil your responsibilities.

Firstly there are two documents that are extremely useful in understanding, namely Legionnaires’ disease - The control of Legionella bacteria in water systems (download here), BSRIA have also published Legionnaires' Disease Risk Assessment dated 2015 referenced (BG57/2015) advising on best practice on assessing risk. Fundamentally, they focus on the following;

  • Make sure that everyone in your building is protected from the health risks created by Legionella.
  • Carry out a risk assessment.
  • Introduce measures to reduce the risks from Legionella for your tenants.

What happens when contracting legionella?

The most serious condition arising from Legionella bacteria is Legionnaires’ disease which affects between 200-300 people each year in the UK. The disease is most common amongst those over the age of 50 who have a weaker immune system and are more susceptible to illness.

Where is Legionella Found?

Legionella bacteria are most commonly found in man-made water systems (such as water-based air-conditioning systems such as chilled water systems, domestic hot water tanks, like those that supply baths and showers and whirlpool baths).

In fact, they can thrive in any place where water is maintained at a constant temperature.

What Factors Make Legionella More Likely?

There are certain conditions which increase the risks from Legionella. These are:

  • The water temperature is between 20-45°C (the most suitable temperature for the growth of bacteria).
  • The water droplets, sprays or mists are dispersed into the air.
  • The water has been stored and/or re-circulated before use.
  • There is a source of nutrients for the bacteria in the water, such as rust or sludge.
  • If any of these conditions are present then the chances of Legionella causing harm to tenants is increased.

Temperatures range for Legionella:

The bacteria is killed over a period of two or so hours by increasing the temperature of the water to around 55 degrees Celsius.

Can I Get a Compliance Certificate?

A sample of water from these relevant systems are taken to a laboratory for testing and a result sheet / certificate of the composition of water is provided including the parts per million of various bacteria such as TVC and Legionella. A separate sample for Pseudomonas (also a risk factor based on micro-biological testing) can be undertaken using a separate sample basis.

Unlike Gas Safety, there are no specific landlord certificates or registers that you can join to prove Legionella safety. Chemical testing of closed water and domestic water systems are however recommended as also recommended as part of a water hygiene risk assessment.

While these test certificates are not mandatory, the impact they have on safety could be invaluable.

Control Measures for Legionella

The broad requirements for controlling Legionella bacteria in water systems are:

  • Appointment of a responsible person (in a managerial rather than technical grade)
  • Formal Legionella risk assessment with suitable and sufficient documentation of findings, including schematics detailing the water system
  • Ongoing review and reassessment of Legionella exposure risk
  • Development of a risk minimisation programme, a prioritised action plan and a mechanism for escalating remedial work where risk assessment and monitoring data indicate a risk
  • Implementation and management of the programme
  • Development of formal procedures for inspection, maintenance and disinfection of water systems
  • Training of staff
  • Maintenance of suitable records.

Assessments should be reviewed at least biennially and when they may no longer be valid, for example when changes are made to the use of the building in which the water system is installed. Where risk assessment identifies a significant risk, you should arrange for the system to be disinfected immediately, either thermally or by chemical means.

How to Do a Legionella Risk Assessment

A risk assessment is simply a careful examination of what could cause harm to people. This way, you can weigh up whether you have taken enough precautions or need to do more.

The main steps in the risk assessment process are:

  • Identify the hazards.
  • Decide who might be harmed and how.
  • Evaluate the risks and implement controls.
  • Record your findings.
  • Review your assessment and update if necessary.

Legionella risk assessment records should include details about:

  • Any significant findings of the risk assessment (include all the Legionella risks that you have identified).
  • The control measures needed and how you plan to implement them (including time-scales for when they will be done).
  • Details about the state of operation of the water system (whether it’s in use or not in use.)
  • The results of any monitoring, inspections, tests or checks that have been carried out, and the dates of these. has produced a handy factsheet with more information on their website here.

Karsons undertake auditing of all building documentation where water hygiene is covered in a unique section. Here we review the water hygiene risk assessment initially, but critically water temperatures, chemical and bacterial testing is also reviewed to ensure safe water systems.