Stormwater means water collected from trafficable surfaces, including paved or ground surfaces. A stormwater tank is designed to capture and store stormwater.

BASIX assesses stormwater based on:

  • Size of the stormwater tank you are installing in litres, being the volume available for water storage in addition to (i.e. excluding) any requirement for stormwater detention or retention for your site.
  • Area of the catchment (i.e. water collection area) to be connected to the stormwater tank. This is entered by catchment type.
  • Uses the water from stormwater tank will be allocated to, depending on whether it is treated or untreated.

Roof areas can also be diverted for collection in a stormwater tank (rather than a separate rainwater tank) however untreated stormwater can only be used for garden irrigations (and should not be used on edible plants).

Treated stormwater can be re-used for garden irrigation, toilet flushing, and laundry (cold water washing machine) use, provided it meets the requirements set by NSW health.

As a guide, the use of treated and untreated stormwater for garden irrigation is subject to the same constraints and environmental protection measures as apply to greywater re-use.

The volume of the stormwater tank specified as part of BASIX water commitments must be in addition to any minimum tank requirements specified by the local council for detention and/or retention.

Multi unit developments may also select the option of a central water tank to collect and supply water to common area uses or the individual dwellings.

Further information:

You should contact your local council and/or a professional hydraulic engineer for further information regarding the design and installation of stormwater tanks in your area.

Stormwater Industry Association promotes innovative and sustainable practice technologies, standards and policies that minimise adverse environmental, social and economic impacts.