Overview of changes – plumbing and drainage

We’re providing a series of articles to give you a snap shot of some changes that may impact your work when NCC 2022 is adopted by states and territories.

Open up the NCC, and we’ll step you through some of the key changes to the plumbing and drainage requirements in NCC 2022.

Remember, NCC 2022 also has a new referencing system. We’ve included the previous NCC 2019 references, to help you identify what has changed.

Volume Three introduces new requirements for any plumbing product containing copper alloy and intended for use in contact with drinking water from 1 September 2025.

Detail on the changes to the lead requirements for plumbing products are covered in our separate advice to practitioners.

Measurable compliance criteria are added to the Performance Requirements for:

• water services velocity and pressure;
• heated water pressure relief and temperature limitation;
• fire-fighting water service flow rates and pressures; legionella control; and
• water efficiency (based on WELS rating standards).

These allow more consistent verification of Performance Solutions for water services.

A new risk assessment-based Verification Method B5V1 is in Part B5 for individual and zone hazard ratings for backflow prevention.

This method includes a series of tables outlining risk factors for different building types, water services, drinking water usage, cross-connection types and the extent of possible contamination. It also enables calculation of a hazard rating for situations not covered by the DTS Provisions. Several DTS hazard ratings are revised in Specification 41 for known cross-connection hazards.

Part B6 (Rainwater harvesting and use) is split into 2 Parts, Part B6 – Rainwater services, and Part B7 – Rainwater storage.

Measurable compliance criteria are added to the Performance Requirements for ventilation and pressure of sanitary plumbing and drainage services. These provide more consistent verification of Performance Solutions for these aspects.

New Verification Methods are in Parts C1 and C2 for determination of wastewater flowrates. These enable more efficient pipe sizing to be used for specific buildings.

A new Part C3 provides a nationally consistent set of requirements for on-site wastewater management and disposal.

A key change to the NCC definitions includes the revision of the existing defined term ‘point of connection’ to clarify its application and includes fire-fighting water services.

AS 3959 is referenced in Volume Three to provide specific requirements in the DTS Provisions for plumbing and drainage systems in bushfire-prone areas.

AS 1546 Parts 1-4 and AS 1547 are referenced in the DTS Provisions for the new Part C3 – On-site wastewater management.

AS/NZS 3500 Parts 1, 2 and 4 are updated to the 2021 editions. These replace the 2018 editions, referenced in NCC 2019.

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