NCC 2022 Volume Three - Plumbing Code of Australia


TAS Part E4 Stormwater surface and sub-surface drainage systems

TAS Part E4 Stormwater surface and sub-surface drainage systems

Introduction to this Part

This Part sets out the requirements for a surface drainage system to a Network Utility Operator's stormwater system or an approved disposal system.

TAS E4O1 Objective2019: FO2

The Objective of this Part is to—

  1. safeguard people from illness, injury or loss (including loss of amenity) due to the failure of a stormwater drainage installation; and
  2. ensure that a stormwater drainage installation is adequate; and
  3. conserve water and energy; and
  4. safeguard the environment; and
  5. safeguard public and private infrastructure; and
  6. ensure that a storm water drainage installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (e).

TAS E4F1 Functional statements2019: DF2.1

Buildings and their surroundings are to be provided with a surface drainage and subsurface drainage installation and be constructed in such a manner as to provide protection for people, property and the environment from the adverse effects of stormwater.

TAS E4P1 Surface drainage systems2019: FP2.1

(1) A surface drainage system must have capacity to transfer the volume of water anticipated in an annual exceedance probability rainfall event.

(2) The annual exceedance probability must be appropriate to the—

  1. importance of the building; and
  2. severity of potential damage to property, loss of amenity, illness or injury that would result from the failure of the system.

TAS E4P2 Subsurface drainage2019: FP2.2

A subsoil drainage system must remove excess groundwater and reduce soil moisture levels to prevent loss by changing soil moisture conditions.

TAS E4P3 Design, construction and installation2019: FP2.3

(1) A surface drainage installation must avoid the following:

  1. Blockage and uncontrolled discharge.
  2. Damage from root penetration, superimposed loads or ground movement.
  3. Entry of sewage and/or liquid trade waste.
  4. Entry of stormwater into a sanitary drainage.
  5. Damage to the Network Utility Operator's drainage system
  6. Foul air and gases accumulating in the stormwater system.
  7. Loss to buildings or property.

(2) A surface drainage installation must ensure the following:

  1. Access for maintenance and clearing blockages.
  2. Stormwater is transferred to a Network Utility Operator's stormwater system or an approved disposal system.

TAS E4D1 Application2019: F2.1

Performance requirements E4P1 to E4P3 are satisfied by complying with E4D2 and E4D3.

TAS E4D2 General requirements2019: F2.2

A surface and subsurface drainage system must comply with—

  1. AS/NZS 3500.3; or
  2. Housing provisions 3.3

TAS E4D3 Protection from surface water2019: H201.2

Surface water must be prevented from escaping a liquid trade waste generating area though the installation of a bund, speed hump or other feature a minimum of 150 mm high surrounding the area.

Explanatory information

Stormwater drains alone may not be adequate as stormwater will often flow over the grate and enter a liquid tradewaste generating area. The total surface water across the site is to be considered and the height of the bund or other feature should be increased where there is a risk of stormwater entering the liquid Tradewaste generating area.

See TAS Figure E3D3 for a typical diagram of roofing and bunding of liquid tradewaste generation areas.