Construction micro-organisms: Legionella from water systems

Work involving water or old / poorly maintained water systems might expose construction workers to Legionella. This page tells you how to control this risk and why. You also need to be aware of the general information on micro-organisms.  

What you must do

Follow the Assess, Control and Review model. Pay particular attention to the following things:


Identify and assess: The risk of being exposed to Legionella is mainly during refurbishment and demolition work. The risks are linked to:


Prevent: Think about limiting the risks before work starts:

Control: Where there is still reason to suspect a Legionella risk, control this by:


Supervise: Be aware of anyone suffering from the symptoms of Legionnaires' disease.

What you should know

The infectious bacterium, Legionella pneumophilia, occurs naturally in water and also in water systems where the temperature high enough to encourage growth; eg hot water systems or water storage tanks in the summer months.

These bacteria can cause illnesses collectively called Legionellosis. This includes the most serious illness, Legionnaires' disease, as well as the similar but less serious conditions of Pontiac fever. Legionnaires' disease is a potentially fatal form of pneumonia.

Updated 2021-08-06