Clause 6.6.2.4.2 "New installations"
In above ground sanitary drainage systems, where a 100mm junction connects a 100mm branch pipe to another 100mm pipe, the entry level of the branch pipe must be rotated to 15° above the horizontal.
The National Construction Code (NCC) 2022, Volume 3, Victorian variation C1D3 amended Clause 6.6.2.4.2 so that for class 1 buildings where the 15° cannot be achieved, the incline must be as close as possible to 15° to avoid stranding.
Clause 4.9.1.2
Clause 4.9.1.2, which only applies to drains below ground, has the same 15° requirements for 100mm junctions in drains and applies to all classes of buildings.
Updated plumbing and drainage standards (AS/NZS 3500 series)
On 17 April 2025, Standards Australia published updated standards for plumbing and drainage parts 1-4 of AS/NZS 3500.1: 2025.
These standards are referenced in the Plumbing Regulations 2018 and Plumbing Code of Australia (PCA).
From 20 October 2025, plumbing practitioners must ensure plumbing work is in accordance with the updated plumbing standards.
We recommend that practitioners familiarise themselves with the updated standards and apply it in their work as soon as practicable.
Please note that clauses 6.6.2.4.2 and 4.9.1.2 will not be affected by these changes, so the guidance above will still be correct and relevant from 20 October 2025.
