Hot Water System Installation SWMS

Hot water system installation covers the supply, installation, connection and commissioning of heated water systems — storage and continuous-flow gas, electric, heat-pump and solar water heaters — including the cold and heated water connections, the temperature control, the relief valves and the safe disposal of relief discharge. Heated water work carries several hazards together: scalding from delivered water that is too hot, Legionella growth where stored water is too cool, the pressure and stored energy of the system, and, for gas units, the combustion and flueing hazards of the appliance. This document is written on the basis that heated water systems are installed by a licensed plumber, and a licensed gasfitter where gas-fired, with delivered-temperature control and relief-valve and discharge arrangements to the standard.

Heated water services are installed to AS/NZS 3500.4, the heated water services part of the plumbing and drainage standard, which sets the requirements for the heated water connection, the temperature control to limit delivery temperature to sanitary fixtures used for personal hygiene, the tempering or thermostatic mixing valves, the pressure and temperature relief valves, and the safe disposal of relief discharge, and which addresses Legionella prevention. Where the system is gas-fired the appliance is installed and commissioned to AS/NZS 5601.1:2022. Delivered water to sanitary fixtures used for personal hygiene must be limited — generally to 50 degrees, and to lower limits in care settings — to prevent scalding. This document coordinates the heated-water-standard, temperature-control, relief and, where gas, the gasfitting controls so the system is installed and left safe.

Hazards identified

9 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Engineering: install the heated water service to AS/NZS 3500.4 — the heated water connection, relief valves, and the temperature control limiting delivery to sanitary fixtures used for personal hygiene to the required maximum, with a tempering or thermostatic mixing valve.
2. 2Engineering: set and verify the storage and delivery temperatures to control both scalding and Legionella — storing at a temperature that controls Legionella while limiting delivered temperature to the fixture maximum.
3. 3Engineering: fit and confirm the pressure and temperature relief valve and any expansion control, and pipe the relief discharge to a safe, visible disposal point so hot discharge cannot scald.
4. 4Administrative: where the heater is gas-fired, install and commission the appliance to AS/NZS 5601.1:2022 with leak testing, ventilation and flueing, by a licensed gasfitter.
5. 5Administrative: isolate electrical supply and coordinate with a licensed electrician for electric and heat-pump water heaters before making or altering electrical connections.
6. 6Engineering: manage the stored energy and pressure of the system — isolating, depressurising and allowing hot water to cool or be safely released before working on the system.
7. 7Engineering: provide safe access and fall-prevention for solar collectors, roof-mounted and split components, with work platforms or harness-based controls for work at height.
8. 8Administrative: ensure the work is carried out and certified by an appropriately licensed plumber or gasfitter under the relevant state or territory plumbing and gasfitting licensing scheme, with a compliance certificate issued where required.
9. 9Administrative: all workers must hold a valid White Card (General Construction Induction Training, CPCCWHS1001) before entering any construction workplace, with the plumbing, gasfitting and any confined space competencies and licences required for the work.
10. 10Administrative: conduct a daily pre-start toolbox talk covering the day's work, identified hazards, isolations, required PPE and emergency procedures, and record attendance in the consultation section.
11. 11Administrative: consult workers and any health and safety representatives on the work and its risks, record the consultation, and keep this document available at the workplace.
12. 12PPE: eye protection to AS/NZS 1337.1, hearing protection where required, gloves appropriate to the task, and Class I or Class II safety footwear with protective toecap to AS/NZS 2210.3.
13. 13Administrative: review and update this SWMS whenever the work scope changes, after any incident or near miss, when a worker or health and safety representative raises a concern, when new hazards are identified, or at minimum every 12 months.

Applicable Codes of Practice

Worked example

A licensed plumber is engaged to replace a storage hot water system with a continuous-flow gas water heater serving a family home. The heated water service is installed to AS/NZS 3500.4, and because the heater is gas-fired a licensed gasfitter installs and commissions the appliance to AS/NZS 5601.1:2022 with leak testing, ventilation and flueing. A thermostatic mixing valve is fitted so that delivered water to the bathroom fixtures used for personal hygiene is limited to the required maximum to prevent scalding, while the heater is set so the system controls Legionella. The pressure and temperature relief valve and expansion control are fitted, and the relief discharge is piped to a safe, visible disposal point where hot discharge cannot scald. The electrical supply for the unit's controls is isolated and coordinated with a licensed electrician. The old unit is isolated, depressurised and allowed to cool before removal, and the new system is commissioned and the delivered temperature verified. The plumber and gasfitter issue their compliance certificates and retain the records.

Related legislation

• Model Work Health and Safety Act — primary duty of care; the duty to consult workers; the reckless-conduct offence; and notifiable-incident provisions, as enacted in each jurisdiction.
• Model Work Health and Safety Regulations — Section 291 high risk construction work and the SWMS preparation and review duties, and the confined space provisions where applicable, as enacted in each jurisdiction.
• The relevant plumbing and drainage standards AS/NZS 3500 (Parts 0–5) and, for gas, AS/NZS 5601.1:2022, are called up by the state and territory plumbing and gas safety legislation.
• Plumbing and gasfitting work is licensed under each state and territory's plumbing and gasfitting licensing scheme, with compliance certification required for notifiable work.
• Victoria operates under the Occupational Health and Safety Act 2004 and the Occupational Health and Safety Regulations 2017, with the high risk construction work and confined space provisions applying in place of the model instruments.

Frequently asked questions