Updates to AS 3500: 2025 Plumbing and Drainage Standards series

This handy resource provides clause references to changes to the current NCC referenced edition, which are likely to come into effect soon.

Standards Australia has published updated versions of the plumbing and drainage standards:

• 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.

These revised editions of the Standards are not referenced in NCC 2022.

Generally, standards are not mandatory unless adopted by legislation such as the NCC. Check with your relevant jurisdiction who will adopt new versions via regulations as amended. E.g. Victorian Building and Plumbing Commission provide a six month transition period for the new standards. In the meantime, use of the standard could be accepted by the relevant authority using a simple Performance Solution.

Key changes

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

• Clause 2.3 New requirements specifying the use of certain classes of flexible hose assemblies in hot, cold and submerged water applications. 
• Clauses 4.4 and 4.6 Minor changes to the backflow prevention provisions for atmospheric vacuum breakers. 
• Clause 5.20 New provisions for the connection of miscellaneous devices and appliances to the drinking water supply. 
• Clause 5.4.2 New requirement for an isolating valve to be installed immediately before each flexible hose assembly is connected to a mixer valve, tap outlet or cistern.

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

• Clause 13.24 New requirements for the installation of waterless urinals to reduce the risk of struvite build up. 
• Clause 13.28 New provisions for the connection of miscellaneous devices and appliances to a sanitary drainage system. 
• Section 14 Updated requirements for the main lines of a sanitary drainage system serving multi-unit developments of three or more residential buildings. 
• Clause 16.2 Polypropylene (PP) pipes and fittings included as an alternative material and product for vacuum drainage systems.

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

• Clause 3 Updated requirements for residential eaves gutter overflows and valley gutters. 
• Clause 5.3.8 New provisions for devices and appliances connected to stormwater drainage systems. 
• Appendix F New mandatory provisions covering overflow design for eaves gutters.

AS/NZS 3500.4: 2025: Plumbing and drainage, Part 4: Heated water services

• Clause 2.3 New requirements specifying the use of certain classes of flexible hose assemblies in heated water applications. 
• Clause 10.10.2 New requirement for an isolating valve to be installed immediately before each flexible hose assembly connected to a mixer valve or tap outlet.