Intervals marked as a regulation, standard or authority requirement are drawn from the NSW Public Health Regulation 2022 as explained by NSW Health, water authority trade waste and backflow policies, and AS/NZS 2845.3, AS 4032.3, AS/NZS 3500.4 and AS/NZS 3666 as summarised by the regulators and the industry. Where an interval is common practice rather than a requirement, it is marked as recommended practice. Section and clause numbers are quoted only where the source states them.
AS/NZS 3500 is the plumbing and drainage installation standard behind the Plumbing Code of Australia; like the electrical Wiring Rules it says how to build a system, and only its operation and maintenance appendix speaks to what happens afterwards. The recurring duties come from elsewhere: the water authority requires testable backflow devices to be registered and tested annually; AS 4032.3 sets the field-test interval for thermostatic mixing valves; the trade waste agreement sets the grease trap interval; and in New South Wales the Public Health Regulation 2022 sets a monthly test, a five-yearly plan and an annual audit for every cooling tower. The other states run equivalent frameworks with their own forms and authorities.
Who does what
Owner and staff tasks are the temperature checks, the visual walks and the paperwork: lodging certificates, keeping the register, watching the reportable thresholds. Everything that involves a test instrument or opening a device is licensed work: backflow testing needs an accredited tester, TMV testing needs a plumber with the TMV endorsement, cooling tower sampling goes to a NATA-accredited laboratory and the risk plan and audit need a competent person who is independent of the occupier for the audit. The owner or facilities manager stays responsible for the schedule and the records whoever attends.
Routine tests and services, by system
Backflow prevention devices
- Register: every testable device (reduced pressure zone valve, double check valve assembly, spill-resistant vacuum breaker) is registered with the water authority when installed.
- Annual: test by an accredited backflow tester with a calibrated differential pressure gauge under AS/NZS 2845.3; the test certificate is lodged with the water authority each year. Where the customer does not lodge, the authority may send its own tester and bill the owner.
- Six-monthly (recommended practice): a visual check of the device body, discharge port, strainer and isolation valve for leaks, corrosion and tampering.
- On failure: the device is repaired or replaced before the supply is reinstated.
Thermostatic mixing valves (TMVs)
- At least every 12 months: field test and service by a plumber holding the TMV endorsement, under AS 4032.3, unless a documented risk assessment sets a shorter interval. The test confirms the outlet temperature, the fail-safe shut-off when the cold supply is isolated, and the condition of the cartridge and strainers.
- Six-monthly in hospitals: NSW Health requires six-monthly TMV testing in hospitals; aged care, childcare and disability accommodation operators commonly adopt the same interval as their risk-assessed setting.
- Monthly outlet temperature check (recommended practice): a calibrated thermometer at each outlet, with anything above 50 degrees at a TMV outlet investigated the same day.
- About five years: replacement of the thermostat and seals, or of the valve, per the manufacturer.
TMVs are required at every accessible outlet in facilities for young children, older people and people with a disability under the plumbing code and state regulations; a valve that has drifted is a scalding risk and a liability, which is why the test record matters.
Hot water systems
- Monthly (recommended practice): storage temperature confirmed at 60 degrees or above, which is the Legionella control point for stored hot water, and delivery temperature at the furthest outlet.
- Six-monthly: the temperature and pressure relief valve's easing lever lifted briefly to confirm it flows and reseats; a valve that weeps afterwards is replaced. This is the maintenance step the plumbing standard's operation and maintenance guidance and every manufacturer set for storage units.
- Annual: service by a licensed plumber (and gasfitter for gas units): relief valve, thermostat, anode condition, flue and burner or element, tank flush.
- Three to five years: sacrificial anode replacement per the manufacturer; the relief valve is commonly replaced at five years.
Cooling towers (NSW Public Health Regulation 2022)
- Weekly: visual inspection of the tower, drift eliminators, make-up water and leaks; the unique identification number sign in place.
- Monthly: water treatment chemistry per AS/NZS 3666.3, and sampling for Legionella and heterotrophic colony count by a NATA-accredited laboratory.
- Within 24 hours: a reportable result (Legionella at or above 1,000 cfu/mL, or heterotrophic colony count at or above 5,000,000 cfu/mL) is notified to the local council on the approved form, and the AS/NZS 3666.3 control response starts.
- Six-monthly: mechanical inspection and clean of fill packs, drift eliminators, basin, screens, fan and drive.
- Annual: disinfection of the circuit; and an 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.
- Every five years: a risk management plan prepared by a competent person, or sooner if the system or its risk changes, with the certificate of completion lodged within seven days.
- Notifications: installation and a change of occupier within one month, decommissioning within seven days, and the unique identification number displayed on a durable sign of at least A5 within 30 days of issue.
Cooling towers are the one water asset where the interval is written into public health law rather than a standard. Warm water systems in hospitals, aged care, hairdressing and childcare premises are notified to council under the same Regulation and operated to AS/NZS 3666.2. Other states run equivalent schemes; check the health department of the state the building is in.
Grease traps
- Per the trade waste agreement: pump-out and clean by a licensed trade waste contractor at the interval the water authority sets from the kitchen's load. Sydney Water schedules 4, 8, 13 or 26 weeks and the business cannot choose its own; monthly is common for an active club or restaurant kitchen.
- At each service: grease and sludge depths measured (a grease mat over a quarter of the trap depth, or sludge over 30 per cent, means a shorter interval), baffles, tees, seals and cover hardware inspected, and a cleaning certificate issued.
- Records: the certificates are kept and reported as the agreement requires; the authority can pump the trap at the owner's cost and issue infringement notices where the schedule lapses.
Rainwater and non-potable supplies
Where a rainwater tank tops up from mains, the backflow device on the top-up line joins the annual test above, the cross-connection to drinking water is checked annually, screens and first-flush diverters are cleaned quarterly, and the tank is desludged every three to five years, under the rainwater provisions of AS/NZS 3500.1. Non-potable pipework carries the lilac marking and signage the standard requires.
What the owner has to lodge and keep
The annual backflow test certificate, lodged with the water authority and kept. The TMV test and service record for each valve, with the outlet temperature readings. The hot water service record and relief valve replacements. For a cooling tower: the council register entry and unique identification number, the monthly laboratory results, any reportable-result notification, the risk management plan and its certificate, and the annual audit certificate, all kept on site and available to the council. For a grease trap: every cleaning certificate and the trade waste reports.
Turning the schedule into a register
The intervals above only hold when every backflow device, TMV, hot water unit, cooling tower and grease trap in the building is listed with its interval, its contractor and where the certificate lives. That is an asset register with a maintenance planner on top of it. Standara's library carries these assets with the tasks and intervals attached, so selecting what the building has produces the 12-month schedule, and the compliance report is the record the water authority, the council or the insurer asks for. How to build a facilities asset register covers the site walk; the AS 1851 maintenance schedule and the electrical testing schedule cover the fire and electrical systems that sit beside these on the same statement.
Related
- AS 1851 maintenance schedule: the fire protection intervals and the NSW record-keeping duty.
- Electrical testing schedule: RCDs, test and tag, switchboards and emergency lighting.
- HVAC maintenance schedule: air conditioning, ventilation, refrigerant, kitchen exhaust and smoke control, with the rule behind each interval.
- Lift maintenance schedule: lift and escalator servicing, annual inspection and plant registration.
- Maintenance software for clubs: the kitchen, cellar and pool assets a club has to keep on schedule.
You now have the test rhythm for every water system in the building, the authority behind each interval, and the certificates that prove it.