AS/NZS 3500 is a series of standards that address the requirements for plumbing and drainage systems in various applications. This series supports the design, construction, and maintenance of plumbing systems for safe and efficient operation.
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Understanding the AS/NZS 3500 series

The AS/NZS 3500 series is divided into several parts, each focusing on different aspects of plumbing and drainage:

• AS/NZS 3500.1: 2025, Plumbing and drainage, Part 1: Water Services

• AS/NZS 3500.2: 2025, Plumbing and drainage, Part 2: Sanitary Plumbing and Drainage

• AS/NZS 3500.3: 2025, Plumbing and drainage, Part 3: Stormwater drainage

• AS/NZS 3500.4: 2025, Plumbing and drainage, Part 4: Heated water services
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These standards work together to provide a holistic approach to plumbing and drainage, helping to guide the design and maintenance of systems to high standards of safety and efficiency.
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Key updates to the AS/NZS 3500 series in 2025

The AS/NZS 3500 series has undergone significant updates in 2025 to reflect advancements in technology and safety practices. Some of the key changes include:

1. Atmospheric vacuum breakers (AVB): Changes in Part 1, Section 4, and Table 4.4 align the standards with international practices, elevating AVBs to high hazard testable devices. This aims to provide plumbers with more options for high hazard backflow protection.

2. Flexible hoses: Updates in Parts 1 and 4 aim to reduce the risk of failure of flexible connectors and subsequent water damage. New provisions align with AS 3499: 2022, Water supply – flexible hose assemblies , helping to guide the appropriate use of flexible hoses and the installation of isolation valves where necessary.

3. Miscellaneous appliances, devices, and fixtures: The series now includes deemed-to-satisfy provisions for the connection of various appliances and devices, supporting safe and technically sound installations.

4. Multi-building developments: Changes in Part 2 clarify the requirements for sanitary drains in multi-unit developments, which aims to reduce the risk of non-adherence and improve clarity for industry professionals.

5. Polyethylene water pipes: New requirements address the installation of higher-pressure classes of polyethylene pipes in northern Australia, where certain conditions have led to shortened pipe life expectancy.

6. Design rules for eaves gutter overflow and valley gutters: Part 3 now includes design rules for roof drainage that seek to be clearer and more easy-to-interpret, aiming to support adherence and reduce confusion.

7. Waterless urinals: Updates in Parts 1 and 2 address the build-up of struvite in waterless urinals, introducing new requirements for minimal grading and cleansing flushes that aim to reduce maintenance costs and improve bathroom environments.

8. Polypropylene pipes for vacuum drainage: Part 2 now includes polypropylene pipes as a suitable material for vacuum drainage systems, keeping the standard in line with international practices and innovations.
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Benefits of the AS/NZS 3500 series 2025 updates

The AS/NZS 3500 series in 2025 brings targeted updates that aim to support safer, clearer and more future-focused plumbing and drainage practices. Potential benefits could include:

• Greater flexibility and choice – Updates to high hazard backflow protection and pipe materials (like polypropylene for vacuum drainage) provide more solutions without relying on performance-based pathways.

• Clearer guidance – New deemed-to-satisfy provisions, along with clarified requirements for roof drainage and multi-building developments, aim to reduce ambiguity and simplify installation planning.

• Lower maintenance – Changes to waterless urinal design and flexible hose specifications are intended to reduce wear, struvite build-up, and costly callouts.

• Longer system life – Installation rules for polyethylene pipes in northern Australia address known risk areas and aim to prevent premature pipe failure.

• Alignment with international practices – Harmonising elements such as AVBs and material standards can support the industry in keeping in step with global innovations.
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Who is the AS/NZS 3500 series for?

The AS/NZS 3500 series supports a wide range of professionals working with plumbing and drainage systems. The 2025 updates could potentially benefit professionals in several ways:

• Plumbers and installers – Updated installation guidance across flexible hoses, appliances, and roof drainage can help support safer, more consistent work on site.

• Regulators and certifiers – Clearer provisions for multi-building developments and new deemed-to-satisfy rules could assist with inspections and enforcement.

• Construction and maintenance teams – Design rules and material updates could help reduce rework and future maintenance needs.

• Manufacturers and suppliers – Incorporation of new products and materials (like polypropylene for vacuum drainage) could support product uptake and relevance.

• Facility managers and owners – Measures like the struvite control in urinals and clearer hose rules could reduce long-term damage and maintenance overhead.

• Training providers and educators – The series offers a comprehensive, updated resource for teaching best practice and preparing future professionals.
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The AS/NZS 3500 series are vital standards that provide a framework for the safe and efficient use of plumbing and drainage systems. By following these standards, industry can help support safety and operational excellence.

The standards are available through the Standards Australia Store and our distribution partners.

The AS/NZS 3500 series is available through the Standards Australia Store and our distribution partners.

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