AS 3500.1 Plumbing and Drainage
Protect your home and plumbing infrastructure with full compliance to Australia’s water service standard.
This page breaks down the key sections of AS/NZS 3500.1:2003 — so you understand your obligations, what professionals inspect, and how these standards impact plumbing installations in residential and commercial properties across Australia.
What is AS/NZS 3500.1 2003?
AS/NZS 3500.1:2003 is the Australian/New Zealand Standard for plumbing and drainage relating specifically to water services. It outlines how cold and non-drinking water systems must be designed, installed, and maintained to ensure safety, reliability, and compliance with the Plumbing Code of Australia (PCA).
It applies to:
New water service installations
Repairs or alterations to existing water systems
Cold water supply systems (including rainwater or non-drinking water)
Who Needs to Comply?
The standard is relevant for:
Licensed plumbers and contractors
Property developers and builders
Inspectors and certifiers
Homeowners doing renovations or upgrades
Key Topics Covered in the Standard
Section 1 – Scope & Definitions
Introduces the standard’s purpose, its scope of application, and key terminology.Section 2 – Materials & Products
Lists approved materials for pipes, fittings, joints, and storage tanks.Section 3 – Sizing Water Services
Provides guidelines on flow rates, pipe sizing, and acceptable velocity limits for efficient water supply.Section 4 – Cross-Connection & Backflow
Details the methods to prevent contamination of potable water through proper backflow prevention.Section 5 – Cold Water Installation
Covers requirements for pipe burial depths, insulation, earthing, and protection from mechanical damage.Section 6 – Fire Services
Sets out standards for materials and installation of water supplies used in fire protection systems.Section 7 – Irrigation Systems
Includes standards for garden and landscape irrigation, especially regarding backflow protection.Section 8 – Water Storage Tanks
Describes requirements for water tank design, labelling, overflow handling, and safety.Section 9 – Non-Drinking Water Systems
Covers the safe installation of systems using greywater or rainwater, with separation from potable water.Section 10 – Flushing Water for Sanitation
Outlines specifications for toilet cisterns, urinals, and flushing systems.Sections 11–16 – Pumps, Testing & Commissioning
Includes standards for pump installation, water meter setup, system testing, and compliance verification.
Why This Standard Matters for You
Backflow Prevention: Protects your home’s drinking water from contamination.
Efficient Flushing Systems: Ensures toilets and urinals use the right amount of water.
Safe Rainwater Use: Proper storage and filtration of rainwater for garden or grey use.
Correct Installation Depths: Prevent pipe bursts, frost damage, or electrical hazards.
Fire Safety: Adequate water supply to hydrants and sprinklers in emergencies.
If you’re buying a home or renovating — your plumbing should be checked for compliance with AS/NZS 3500.1 to prevent issues, especially during inspections.
Common Plumbing Defects We Find in Inspections
Unapproved materials used for drinking water pipes
No backflow prevention devices installed
Incorrect pipe depths in high-traffic or public areas
Cross-connection between potable and non-potable water
Unsafe flexible hose use in non-accessible areas
Book an Inspection in Perth
If you're planning renovations, purchasing a property, or just want peace of mind — ensuring your plumbing complies with AS/NZS 3500.1 can prevent costly repairs and health issues. Our licensed building inspectors check against these standards during all inspections.
FAQ
1. Do I need to upgrade my plumbing if it doesn’t meet AS 3500.1?
Only if you're making changes, repairs, or new installations. However, non-compliance could risk insurance issues or health hazards.
2. Can I use rainwater for toilets and gardens?
Yes — but it must be installed with cross-connection controls, backflow prevention, and proper labeling.
3. How deep should pipes be buried?
Depth varies: in public areas typically 450mm, and private areas 300mm or more, depending on pipe material.
4. What’s a common cause of failed plumbing inspections?
Missing or incorrect backflow prevention devices and incorrect materials (like using PVC where copper is needed).
5. Who enforces compliance?
Your local council or water authority, and in some cases, licensed building inspectors like us.
6. Can I install plumbing myself if I follow AS 3500.1?
No. While the standard provides technical guidance, only licensed plumbers are legally allowed to perform water service installations and issue compliance certificates in Australia.
7. What is backflow, and why is it dangerous?
Backflow occurs when water flows in the opposite direction—from a contaminated source into your drinking water supply. This can happen during pressure drops and poses serious health risks, which is why AS 3500.1 mandates certified backflow prevention devices.
8. Do hot water systems fall under this standard?
Partially. AS 3500.1 covers cold and non-drinking water systems. For hot water, refer to AS 3500.4, which is specific to heated water services. However, both must be installed in a coordinated and compliant way.
9. What documentation should a licensed plumber provide?
Upon completion, you should receive a Certificate of Compliance confirming that the work meets AS 3500 and local regulations. This is often required for council approvals and future resale.
10. Does AS 3500.1 apply to commercial properties too?
Yes. Although often associated with residential construction, the standard also applies to commercial and industrial plumbing systems, with additional requirements based on usage, pipe size, and water source type.