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Building Sustainability (BASIX) and Rainwater System Requirements in NSW

Building Sustainability (BASIX) and Rainwater System Requirements in NSW

New South Wales’ Building and Sustainability Index (BASIX) aims to achieve up to a 40% reduction on the consumption of potable water against the state benchmark. This benchmark is explicitly expressed as being equal to 90,340 litres of water per person per year.

BASIX assessment is required for:

  • new buildings that consist of one or more dwellings
  • conversions of an existing building to a building that consists of one or more dwellings
  • additions and/or alterations to buildings that consist of one or more dwellings with an estimated work cost of $50,000 or more
  • swimming pools with capacity of 40,000L or more.

Rainwater Harvesting & BASIX

Rainwater harvesting systems are a great way to achieve BASIX certification for new developments. Rainwater collection is generally assessed based upon:

  • the capacity of the rainwater tank being installed
  • roof catchment area that will be connected to the rainwater tank
  • how the tank water is used
  • running overflow from your rainwater tank to another tank for collection and re-use.

In terms of water tank requirements, BASIX offers you a great deal of freedom in the selection of a water tank, but does state some basic requirements which you must address when making your choice.

Detailed information can be found in NSW Government’s BASIX: Rainwater Harvesting System Guidelines.

Benefits of BASIX Compliance

Being compliant with BASIX has a number of advantages including saving on your bills by using less mains water, enabling you to water the garden whenever it needs to be watered, to wash the car, boat or house when necessary, or to top up the pool or spa, and last but not least, it can add a significant value to your property.

In terms of water consumption, the certificate requires an achievement of a set target, which represents the percentage of saved water against the NSW benchmark of 247 litres per person per day, the 40% reduction of potable water consumption for coastal NSW.

Sustainable Rainwater Harvesting System

Your particular site will require you to calculate the optimum size water tank that will enable you the most effective use of harvested rainwater. There are three main areas that you should consider when using rainwater to help the state of NSW become more sustainable with water:

  1. Local rainfall. You should use the local rainfall data to assist you in determining the potential for capturing rainwater, and consequently, the determining of the water tank size. The Bureau of Meteorology’s rain radars can provide you with accurate information regarding local rainfall, including data such as yearly variations, rainfall seasonality, and occurrence of dry spells.
  2. Surface area. The surface area of roofs and the like are important as 1mm of rain falling on 1 square metre of roof yields 1 litre of water. Most roof materials allow for rainwater to be harvested as “rainwater”, but for driveways, pavements and any water on ground surfaces such is deemed “stormwater” but can still be used to top up pools, for irrigation and the outdoor use.
  3. Water usage. Your water usage is also important and you should base it on the potential uses of the harvested rainwater, which may include irrigation, toilet flushing, laundry, hot water use, pool and spa topping, and drinking and household usage. Installing water efficient devices can help you be more sustainable.

If you are looking to install a rainwater tank in your building project, Team Poly service various areas in NSW and can put you in touch with suppliers for areas not directly serviced. Check out our diverse range of poly water tanks or contact our expert team for advice today.