Small scale stormwater quality model S3QM


The S3QM tool has been recently updated. A number of these updates have been made to provide clarity and improve useability. One major update now allows for developments of any size the ability to receive a deemed to comply solution. 

S3QM is our small scale stormwater quality model online deemed to comply tool.  It was developed to enhance and improve the development assessment process. The tool identifies which stormwater related development controls are applicable, and then assists the user to develop a simple deemed to comply approach.

The core water quality model underpinning S3QM, characterises the impacts of urban stormwater at the development stage.  A range of treatments can be modelled, and users can quickly experiment with different treatment characteristics, or use the 'Size Treatment' option to have S3QM compute an optimal treatment size to meet our water quality objectives.

The S3QM tool is specifically configured to include all the data needed to undertake stormwater assessments in Blacktown - no need to hunt for data, and no risk of inconsistent approaches. It uses local modelling and refers to Blacktown’s development policies.

This on-line tool is user friendly and can be used to develop solutions which satisfy the water quality, water conservation and on-site stormwater detention (OSD) requirements of our Development Control Plan (BDCP) - Part J.

How does it work?

It works much like BASIX where the user develops a complying solution through prompted inputs.  When complete a “deemed to comply” certificate is generated which can be digitally submitted to us.

The certificate is assessed, along with the development assessment submission and used to verify the details on the submitted development application drawings.

Developments of any size can use the tool to size OSD basins and water quality systems. There is also an option to model temporary detention basins. 

The current version does not model proprietary water treatment devices such as filter cartridges.

You can access the tool here:

For further information please refer to our factsheets and Blacktown DCP - Part J.

If you have any suggestions or questions about S3QM please email us at