AS/NZS 3500.3:2025 Plumbing and drainage, Part 3: Stormwater drainage
Standards Australia/Standards New Zealand
Supersedes: AS/NZS 3500.3:2021 Plumbing and drainage, Part 3: Stormwater drainage
Draft Designation: DR AS/NZS 3500.3:2023This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee WS-014, Plumbing and Drainage, to supersede AS/NZS 3500.3:2021.
The objective of this document is to provide stormwater drainage solutions to comply with —
(a) the National Construction Code (NCC); and
(b) the New Zealand Building Code (NZBC), Clause E1 Surface Water.
A list of all parts in the AS/NZS 3500 series for plumbing and drainage can be found in the Standards Australia and Standards New Zealand online catalogues.
The major changes in this revision are as follows:
(i) Updated requirements for residential eaves gutter overflows and valley gutters, see Clause 3 and Appendix F.
(ii) New requirements for the connection of miscellaneous devices and appliances to the
stormwater drainage systems in Australia, see Clause 5.3.8.
(iii) New requirements for the design and installation of rainwater harvesting systems in New
Zealand, see Section 11.
Notes or footnotes to tables or figures that are expressed in mandatory terms are deemed to be requirements of this document.
Notes to clauses in this document are informative only and do not include requirements.
The terms “normative” and “informative” are used in documents to define the application of the appendices to which they apply. A “normative” appendix is an integral part of a document, whereas an “informative” appendix is only for information and guidance.
This document includes commentary on some of the clauses. The commentary directly follows the relevant clause, is designated by “C” preceding the clause number and is printed in italics in a box. The commentary is for information and guidance and does not form part of the document.
Originated as part of AS CS 3-1931. AS 3500.3.1:1998 and AS/NZS 3500.3.2:1998 jointly revised and redesignated as AS/NZS 3500.3:2003. Previous edition 2021. Fifth edition 2025.
Contents:
Section 1: Scope And General
Section 2: Materials And Products
Section 3: Roof Drainage Systems — Design
Section 4: Roof Drainage Systems — Installation
Section 5: Surface Water Drainage Systems — Design
Section 6: Surface And Subsoil Drainage Systems — Installation
Section 7: Surface Water And Subsoil Drainage Systems — Ancillaries
Section 8: Pumped Systems
Section 9: Site Testing
Section 10: Siphonic Drainage Systems
Section 11: Rainwater Harvesting Systems (New Zealand Only)
Appendix A: (Informative) Site-Mixed Concrete For Minor Works
Appendix B: (Informative) Stormwater Drainage Installation Plans
Appendix C: (Informative) Guidelines For Determining Rainfall Intensities
Appendix D: (Normative) Rainfall Intensities For Australia
Appendix E: (Normative) Rainfall Intensities For New Zealand — 10 Min Duration
Appendix F: (Normative) Overflow Design For Eaves Gutters
Appendix G: (Informative) General Method For Design Of Eaves Gutter Systems — Example
Appendix H: (Normative) Box Gutter Systems — General Method, Design Graphs And Illustrations
Appendix I: (Informative) Box Gutter Systems — General Method — Examples
Appendix J: (Informative) Surface Water Drainage Systems — Nominal And General Methods — Examples
Appendix K: (Informative) Example Calculation — Pumped System
Appendix L: (Informative) Subsoil Drainage Systems — Design
Appendix M: (Informative) General Information
Appendix N: (Informative) Operation Of Siphonic Roof Drainage Systems
Bibliography
Plumbing and Drainage.
WS-014
Association of Hydraulic Services Consultants Australia; Association of Hydraulic Services Consultants Australia (New Zealand); Australian Building Codes Board; Australian Gas Association; Australian Industry Group; Australian Stainless Steel Development Association; Australian Steel Institute; Backflow Prevention Association of Australia; Chartered Institution of Building Services Engineers ANZ; Engineers Australia; Hydraulic Consultants Association Australasia; International Copper Association Australia; Master Plumbers Australia and New Zealand; Master Plumbers, Gasfitters and Drainlayers New Zealand; Ministry of Business, Innovation and Employment (MBIE); Plastics New Zealand; Plumbers, Gasfitters and Drainlayers Board; Plumbing Distributors Association of New Zealand; Plumbing Products Industry Group; The Institute of Plumbing Australia; Water New Zealand; Water Services Association of Australia.
