What are the proposed changes?

We are proposing changes to NCC Volume Three to improve the plumbing and drainage provisions.

These changes include:

  • A new Verification Method for cold water service velocity (B1V1)
  • Updated cross-connection control provisions (Specification 41, B5D7)
  • Enhanced rainwater storage provisions (Parts B6, B7)
  • Improved Verification Methods for sanitary plumbing pipe sizing (C1V1, C1V2)
  • Clarifying Performance Requirements (various).

Why are these changes proposed?

These proposed changes are based on industry feedback and our ongoing research. Overall, the changes aim to provide flexibility in compliance, make the NCC easier to use, improve clarity, and align the requirements with relevant standards.

More information on each of the proposed changes is below.

Cold water service velocity Verification Method 

We’re proposing a new Verification Method for cold water service velocity. This will provide practitioners with an alternative method to demonstrate compliance with the Performance Requirements.

Cross-connection control

We’re proposing the current Specification 41 Cross-connection hazards be replaced with a new Deemed-to-Satisfy (DTS) Provision in Part B5 Cross-connection control. The changes also include clarification of the Hazard scenario descriptions.

Rainwater improvements

We’re making changes to clarify and enhance the current rainwater storage provisions. This includes new provisions covering discharge, tank access, top-up line isolation and contamination control in line with AS/NZS 3500.1.

Sanitary pipe sizing Verification Methods

Our research indicated the current sanitary plumbing pipe sizing Verification Methods may not be producing the intended level of performance. In response, we’re proposing to replace Verification Methods C1V1 to C1V5 with improved Verification Methods C1V1 and C1V2 for the next edition of the NCC.

Clarifying Performance Requirements 

There are some existing Performance Requirements that are phrased in a way that can be unclearly interpreted by some practitioners. We’re proposing to improve the wording for the next edition of the NCC to clarify the requirements.

How were the changes developed?

These proposed changes stem from the ABCB’s plumbing research projects. We have engaged with the Plumbing Code Committee (PCC), the ABCB’s technical plumbing advisory committee, technical reference groups and consultants to propose changes for water services, sanitary plumbing, and drainage.

Who has been involved?

In addition to the PCC, several stakeholders including technical reference groups, academic institutions and consultants have been involved in the development of proposed changes to improve plumbing provisions in Volume Three.

What are the impacts?

The proposed changes are expected to bring overall benefits for practitioners and users of plumbing systems. These changes don’t increase stringency, instead they clarify the provisions, and make the NCC easier to use.

To read the full details of the changes, please review the NCC 2025 Volume Three PCD and Section A.

Want to provide feedback?

Responses to the Public Comment Draft are invited until 11:59 PM AEST Monday 1 July 2024.

In line with the ABCB's process for undertaking public consultation, comment will only be accepted through the ABCB's online Consultation Hub.

To access the Public Comment Draft and response form:

  1. Download the NCC volume(s) you wish to view and provide comment. You can also download the supporting information PDF for detailed information on the more significant/complex changes.
  2. Download the response form.

Once you’ve reviewed the draft, complete the response form, and include your feedback on the suggested changes to the NCC.

To submit your comments:

  1. Enter our Public Comment Draft consultation hub.
  2. Start by agreeing to the privacy statement.
  3. Let us know if you’d like your submission published publicly.
  4. Enter your contact details.
  5. Upload your completed form in .doc format (please make sure each file is under 25MB) and submit.