Key messages

  • The Public Health and Wellbeing Regulations 2009 require cooling tower systems to be continuously and effectively treated with one or more biocides to effectively control the growth of microorganisms, including Legionella.
  • This page provides information about what to do following detection of Legionella in a cooling tower system.
  • The department’s Legionella Team must be notified immediately via telephone, and within 3 days via email, if Legionella is detected in two consecutive water samples.

Background

The Public Health and Wellbeing Regulations 2009 require cooling tower systems to be continuously and effectively treated with one or more biocides to effectively control the growth of microorganisms, including Legionella.

Cooling tower systems should also be continuously treated with chemicals and other agents to minimise scale formation, corrosion and fouling, and with a biodispersant.

{…responsible person…} is responsible for the operation of the cooling tower system within {…company name…}. If he/she is unavailable, {…emergency contact…} is to be contacted.

{…water treatment provider…} is employed to undertake the maintenance, cleaning and bacterial testing of the cooling tower system.

If Legionella is detected, {…water treatment provider…} will telephone or email {…responsible person…} with the initial results, and then send a written report with the results of heterotrophic colony count (HCC) and Legionella tests by email.

Phone numbers:

Responsible person:

Emergency contact:

Water treatment provider:

Legionella detection

If Legionella is detected in a sample of water taken from the cooling tower system at {site address}, the following actions will be taken:

  1. {…responsible person…} will contact the water treatment provider to arrange for the disinfection (113) of the cooling tower system, and review (114) the water treatment program, tower operation and maintenance program of the system. The water treatment provider will correct any faults identified within 24 hours of the Legionella notification.
    {…responsible person…} will advise people in the manner described and listed in the following table , and continue to communicate with these stakeholders as the Legionella detection is addressed.
    {…responsible person…} will arrange for {…water treatment provider/other…} to take a sample of water from the cooling tower system and submit it to the laboratory for Legionella testing between 2 and 7 days after the disinfection.
  2. {…responsible person…} will arrange for the water treatment provider to clean the cooling tower system. This means that the cooling tower system will be disinfected, cleaned and re-disinfected.
  3. {…responsible person…} will arrange for {…water treatment provider/other…} to take a sample of water from the cooling tower system and submit it to the laboratory for Legionella testing between 2 and 7 days after the clean.
    1. If Legionella is detected after following the steps above:
  4. {…responsible person…} will repeat steps 3 and 4 until Legionella is not detected in two samples taken approximately 1 week apart, or close the cooling tower system until the problem has been corrected.
    1. If Legionella is detected in three consecutive water samples:
  5. {…responsible person…} will notify the department Legionella Team by telephone immediately and by email within 3 days of receiving notification of the detection.

If Legionella is detected in a second consecutive sample of water:

If {responsible person} is unavailable, {emergency contact} is to undertake the role of the responsible person.

 

Responsibility for notification

Staff

To be advised by (115)

Elected health and safety representatives

To be advised by

Occupational health staff/contractors

To be advised by

Unions

To be advised by

Building owner

To be advised by

Other building occupiers

To be advised by

Medical officer

To be advised by

Staff counsellors

To be advised by

Service contractors

Neighbours of the site

Department’s Legionella Team

1800 248 898

To be advised by

Local council

Environmental health officer

To be advised by

Media liaison officer

To be advised by

Company spokesperson

To be advised by

Chief executive

To be advised by

Footnotes

113. Disinfection of a cooling tower system is achieved by dosing the water of the system with:

  • a chlorine-based compound, equivalent to at least 10 mg/L of free chlorine for at least 1 hour, while maintaining the pH of the water between 7.0 and 7.6; or
  • a bromine-based compound, equivalent to at least 20 mg/L of free bromine for at least 1 hour, while maintaining the pH of the water between 7.0 and 8.5.

114. This review must be documented. It will usually involve the water treatment company and staff with expertise in the process.

115. Once the decision to notify has been made, consideration must be given to the method of notification. This will work best where staff (in particular) have some understanding of the procedures for the cooling tower and the significance of test results, well in advance of notification of the adverse result.