Every month. Under the NSW Public Health Regulation 2022 a cooling tower is sampled monthly for Legionella and heterotrophic colony count by a NATA-accredited laboratory, alongside monthly water treatment under AS/NZS 3666.3. A reportable result (Legionella at or above 1,000 cfu/mL, or a heterotrophic count at or above 5,000,000 cfu/mL) is notified to the local council within 24 hours. The tower is mechanically cleaned six-monthly, disinfected and independently audited annually, and covered by a risk management plan reviewed at least every five years. Other states regulate cooling towers under their own public health rules; the monthly AS/NZS 3666.3 rhythm is common to all of them.
The intervals
| Interval | What happens | Who |
|---|---|---|
| Weekly | Visual inspection of the tower, drift eliminators, make-up water and leaks; the unique identification number sign in place. | Owner or staff, or the water treatment contractor |
| Monthly | Water treatment chemistry per AS/NZS 3666.3 and sampling for Legionella and heterotrophic colony count by a NATA-accredited laboratory. | Water treatment contractor and laboratory |
| Within 24 hours | A reportable result notified to the local council on the approved form; the AS/NZS 3666.3 control response (disinfection, resampling) carried out. | Owner or occupier |
| Six-monthly | Mechanical inspection and clean of fill packs, drift eliminators, basin, screens, fan and drive. | Mechanical or water treatment contractor |
| Annual | Disinfection of the circuit; independent audit of compliance with the risk management plan and the Regulation, with the certificate of audit completion lodged with the council within seven days. | Contractor and an independent auditor |
| Every five years | Risk management plan prepared by a competent person, or sooner if the system or its risk changes; certificate of completion lodged within seven days. | Competent person |
Who does it and what to keep
The occupier of the premises is the duty holder in New South Wales, usually the building owner or the facilities manager on their behalf. The water treatment contractor runs the monthly chemistry and sampling; the laboratory reports; the occupier notifies the council of any reportable result and lodges the annual audit and five-yearly risk management plan certificates. The records are the council register entry and unique identification number, the monthly laboratory results, any notification, the risk management plan, the audit certificates and the six-monthly clean reports, each kept for the period the Regulation sets.
The rule behind the interval
The NSW Public Health Act 2010 and Public Health Regulation 2022 (Part 3, cooling water systems) set the monthly sampling, the 24-hour notification, the annual audit, the five-yearly risk management plan and the notifications on installation, change of occupier and decommissioning. AS/NZS 3666.3 Air-handling and water systems of buildings: Microbial control, Part 3: Performance-based maintenance of cooling water systems, sets the control strategy and the monthly rhythm the Regulation adopts. Victoria's Public Health and Wellbeing Regulations and Queensland's Public Health Regulation carry their own registration and audit rules.
Common questions
What counts as a reportable result?
In New South Wales, Legionella at or above 1,000 colony-forming units per millilitre, or a heterotrophic colony count at or above 5,000,000 cfu/mL. Either is notified to the local council within 24 hours and triggers the control response in AS/NZS 3666.3.
Does a small cooling tower on a club or a shopping centre have the same duties?
Yes. The Regulation applies to every cooling water system, regardless of size. The unique identification number, the monthly sampling, the annual audit and the risk management plan apply to a single tower on a suburban club as they do to a hospital.
Put it in the register
An interval only holds when the asset is listed with its tasks, its contractor and where the record lives. Standara's library carries this asset with the tasks above attached, so adding it to a site's register produces the year's schedule, the monthly to-do list and the completion record the auditor or insurer asks for. The fuller picture, with the neighbouring assets and the rule behind each interval, is in the Water systems testing schedule.
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- A worked example: one club's register, planner and records for a year
- All guides and answers