Blue Mountains City Council and Sydney Water are jointly funding a stormwater treatment initiative within the Knapsack Creek Catchment in Glenbrook. 

The system, designed by Council and Sydney Water, involves the construction of raingardens and a naturalised stormwater channel with embedded biofilters to remove nutrients from stormwater flows that enter the Hawkesbury Nepean River via Knapsack Creek.

This offset project will deliver better waterway health through nutrient removal, creating habitat and improving biodiversity at Knapsack Creek.

It offers a testing ground for Sydney Water to develop innovative monitoring techniques and management practices, and to learn about offset principles and management practices from Blue Mountains City Council.

Sydney Water and Blue Mountains City Council are committed to providing the best outcomes for the environment and the community and aim to minimise the impact of the work on residents and businesses.

We will keep stakeholders informed and aim to provide accurate and timely information during inspections and construction. 

Council will start work in November 2022. Work hours are between 7am and 6pm Monday to Friday and 8am to 1pm on Saturdays.

This work will not affect water or wastewater services.

We encourage community feedback and enquiries on this project. To find out more, please email us at

Frequently Asked Questions:

What is a raingarden?

Raingardens are natural garden beds protecting our waterways from stormwater pollutants. 

How does a raingarden work?

Raingardens are layered with beneficial sediment and plants to reduce the risk of flooding by slowing the flow of stormwater from entering our stormwater systems when there is heavy rain. This also benefits the raingarden by making it self-watering.

How is a raingarden constructed? 

The raingardens will be constructed using sandstone, sand, gravel and local native plants selected for their growth form and capacity to form dense root structures that assist with maintaining infiltration of stormwater and development of biofilms in the root zone that remove pollutants from stormwater. 

Permeable geofabric is usually used on the base of the basin and jute mat and/or mesh on batters and on top of the top layer, to help stabilise until plants establish.

What plants are used in the raingardens? 

Plants selected for the raingardens will be dominated by native sedges grasses/herbs/groundcovers and ferns as most of the raingardens are being built in open space areas where we won’t want to add a lot of shrubs or trees. 

Local tree and shrub species will be planted more in the riparian zones as part of the creekline restoration aspects of this raingardens project.