AS 3500 Plumbing & Drainage Standards in Australia – The Complete Guide (2025 Edition)

Related standards to the AS 3500 Plumbing & Drainage Standards PDF are:

AS/NZS 3500.1 - Water Services

AS/NZS 3500.2 - Sanitary Plumbing and Drainage

AS/NZS 3500.3 - Stormwater Drainage

AS/NZS 3500.4 -Heated Water Services

How well do you know the latest changes to the core plumbing and drainage standard used in Australia? The AS 3500 standard is the Australian plumbing standard for water services, sanitary plumbing and drainage, stormwater drainage, and water heating services. Also known as the AS/NZS 3500 series, it serves a vital role in the National Construction Code (NCC) by providing the technical requirements to meet the performance objectives called for in Volume Three of the NCC.

Volume Three is also known as the Plumbing Code of Australia (PCA), and Australian Standards, such as 3500, provide the best practices for plumbers to follow and remain in compliance with the NCC. That’s why staying current is essential; it ensures compliance with the latest editions of the AS 3500 plumbing standards.

All four parts of AS 3500 are published by Standards Australia, covering sanitary and water systems, as well as their drainage. This guide will explain the scope of each section and how to achieve compliance with the four Australian Plumbing Standards.

As outlined earlier, AS 3500 is the governing series for plumbing and drainage across Australia.
 While these standards are maintained by Standards Australia, they are jointly published with Standards New Zealand (as AS/NZS) to ensure uniformity of plumbing standards across both countries.

Because the NCC specifically references the AS/NZS 3500 series of standards as the best way to meet its requirements, these standards have regulatory importance nationally.

The AS/NZS 3500 series is divided into four parts, with each focusing on different aspects of plumbing and drainage, as outlined in this table:

The previous (2021) version introduced its own updates, including eaves gutter overflow design, valley gutter sizing, appendix revisions, and new definitions.

The current 2025 update includes:

• An additional note for plumbers to give thought to the quantity and quality of stormwater discharge, especially in its potential effects on council infrastructure.
• A requirement (not included in the 2021 version) that the selection of pipework and fittings shall be based on the anticipated discharge temperature (and quality of discharge).
• New eaves gutter overflow measures require them to be designed for at least 1% Annual Exceedance Probability (AEP).
• An update increasing the valley gutter catchment area from 20 m² (in the 2021 edition) to 40 m² (2025 edition).
• Many other changes.

What might you need to review in your designs (if they were based on the 2021 standard)? That depends on your original design parameters, of course, but two obvious things to check are the anticipated discharge temperature and the eaves gutter overflow measures. 

Stormwater Drainage Requirements (AS/NZS 3500.3)

Some of the main requirements in AS/NZS 3500.3 are:

• Sizing the system so that it can handle a 100-year Average Recurrence Interval.
• Specifying a minimum width for all grated trench drains.
• Outlining the requirements for bedding material for the pipes.
• Stating the sufficient gradient to maintain adequate flow.
• Specifications for residential eaves, gutter overflows, and valley gutters.
• Instructions for connecting miscellaneous devices and appliances to stormwater drainage systems in Australia.

Under AS 3500.1 (Water Services), the system design embraces the point of connection to the points of discharge for cold-water services and non-drinking water. The standard includes pipe sizes based on flow, pressure, and velocity requirements, as well as methods of jointing and anchorage below ground. There is also provision for backflow prevention devices and installation of fire services, such as hydrants and sprinklers.

Compliance with AS 3500.1 includes:

• Are the drinking water pipes fit for purpose? Do they meet the required flow rates and pressure? Are they suitable pipes for drinking water?
• Are the backflow prevention devices adequate to prevent contamination of the drinking water?
• Have the underground pipes been installed at the correct depth? Not too shallow?

Under AS 3500.2 (Sanitary Plumbing and Drainage), the system design includes the selection of acceptable pipes and fittings (as outlined in Appendix A), designing a fully-vented system (to prevent sewer gases from entering the building), and designing drainage (such as inspection shafts, boundary traps and reflux valves).

Compliance with AS 3500.2 includes:

• Is the venting adequate to carry away all sewer gases?
• Are the discharge pipes laid at a correct angle (gradient) to adequately carry away all waste without a backlog?
• Is the minimum depth of the fixture trap seals (which prevents insects and gases from entering the building) in compliance with AS 3500.2 specifications?
• Are the termination points of all vent pipes in compliance with the regulations?

What is the compliance process for testing, inspection and certification with the AS 3500 series?

• Design Stage: The design must adhere to the specifications outlined in AS 3500.1 (Water Services), AS 3500.2 (Sanitary Plumbing and Drainage), AS 3500.3 (Stormwater Drainage), and AS 3500.4 (Heated Water Services).
• Installation Requirements: These include roof drainage, stormwater drains, bedding materials, jointing methods and backflow device installation. 
• Testing and Commissioning begin with flushing to remove any foreign matter, followed by hydrostatic testing to detect leaks. Other relevant tests are performed. After testing, commissioning is performed to confirm the correct performance of all valves, cisterns, taps and other components.
• Certification evidence must be provided, including installation photos, test reports, and a signed-off document from a licensed plumber, among other relevant documents. For assistance with the plumbing certification process, visit this page.
• Submission is then made to the relevant enforcement bodies, such as state plumbing authorities, councils, and the Building and Plumbing Commission, among others.


The four AS/NZS 3500 standards can be obtained through Intertek Inform’s Standards Access portal by following these links:

AS/NZS 3500.1 (Water Services)

AS/NZS 3500.2 (Sanitary Plumbing and Drainage)

AS/NZS 3500.3 (Stormwater Drainage)

AS/NZS 3500.4 (Heated Water Services)

These standards are available in hard copy or PDF format, with pricing ranging from approximately $250 to $350 per part. You can register for update alerts to ensure you are always working with the latest version of each standard.

Whether you are designing hot or cold water services, sanitary plumbing or stormwater drainage, you can construct some practical checklists and project documentation templates (which include compliance tools and design resources) that cover:

• Pipe sizing, backflow prevention and compliant water pressure.
• Assigning a hydraulic load value to each fixture to determine the size of the drain and discharge pipes.
• Providing proper ventilation and drainage traps.
• Basing the size of the stormwater drainage system on the roof catchment area and local rainfall intensity (Annual Recurrence Interval).
• Insulation requirements for circulatory piping, orientation of solar collectors, and maximum allowable velocities.

How much training is available for the AS 3500 series to you and your team? Whether you’re a designer, plumber, installer, regulator, certifier, construction and maintenance team, manufacturer or supplier, Intertek Inform can provide you with training courses, webinars and CPD (Continuing Professional Development) programs to ensure you have the knowledge and compliance skills to operate confidently with the plumbing standards. We can also provide certification refreshers or audit preparation services.

In addition to providing access to the latest versions of the AS/NZS 3500 series, Intertek Inform offers expertise in standards interpretation, technical audits, and compliance support.
 Talk to an Intertek Inform expert today!

AS 3500 is the governing series of standards for plumbing and drainage across Australia.
 All four standards were revised in April 2025 to provide the plumbing industry with clear, practical guidance that keeps pace with innovation.

To ensure your full compliance with the AS 3500 plumbing standards, you can contact Intertek Inform for assistance or purchase each standard directly through these links today:

AS/NZS 3500.1 (Water Services)

AS/NZS 3500.2 (Sanitary Plumbing and Drainage)

AS/NZS 3500.3 (Stormwater Drainage)

AS/NZS 3500.4 (Heated Water Services)