If you are an employer who manages a facility that has hot and cold water service or a wet cooling system such as a cooling tower or evaporative condenser, you must be aware of the dangers of Legionella and what measures you can take to guard against it.

Legionella is the bacteria that causes Legionnaires' disease. This sometimes fatal form of pneumonia is contracted when a person inhales tiny water droplets filled with Legionella bacteria. It is not contagious.

Legionella bacteria normally live in bodies of water such as lakes, streams or rivers, but are commonly found in commercial or industrial water systems. They thrive on water contaminated with algae, rust or sludge and can survive water temperatures as low as 4 degrees Celsius.

All employers are legally responsible under general health and safety codes to take the following steps to protect their employees from Legionella.

Identify the potential risk

You must inspect all systems associated with water. These include any showers, heat exchangers or pumps. If conditions exist where either water temperature falls between 20 degrees and 45 degrees Celsius or water droplets are formed that can drift into contact with employees, you must take action.

Prepare a plan of prevention

If you cannot modify a system to eliminate the potential for Legionella growth, you must take steps to minimize the risk. A plan of action must be devised that includes a description of how the company intends to control Legionella. It should include a current and detailed schematic of your water systems, the proper procedures for safe operation of the systems and the name of the person responsible for the assessment and management of the plan. You must also include details of the methods you will use to control Legionella as well as how often they will be performed.

Enact the plan

You must make sure airborne water droplets are reduced or controlled. If possible, avoid water temperatures that promote Legionella growth. Make sure redundant pipework is removed and that water is kept flowing and not stagnant. Remove water contamination to discourage Legionella growth and keep the water clean with water treatments.

Keep adequate records of compliance

All employers with a staff of five or more employees must detail their risk assessment findings and keep a written record of all steps taken to implement your plan. You are responsible for keeping all records for five years.