Strathfield Municipal Council

Grey Water

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Water which has been used within your home for showers, baths, clothes washing, dishwashing, and kitchen sinks is considered Grey Water.

It should be noted that water collected from toilet systems is called Black Water and is heavily contaminated from human excrement and requires a more stringent treatment process.

Grey water is sometimes called waste water however if used appropriately it can be a valuable resource. Grey water can be used immediately (in times of water restriction and without any form of treatment) to water your lawn, however grey water use in your garden requires consideration of the potential impacts of incorrect usage.

The following points highlight the potential impacts if care is not practiced when using grey water in your garden.

  • Soil contamination
  • Over supply of phosphates to native plants
  • Water logging of soil
  • Land slipping and erosion
  • Human health considerations

Various treatment processes can be employed to polish grey water to a standard acceptable for your chosen application. Grey water systems that simply divert the grey water at the time of generation do not require Council approval for installation. Grey water systems that store the grey water for any length of time or treat the grey water must not be installed without Council approval.

Greywater Systems

Greywater is wastewater from:

  • Showers
  • Baths
  • Hand basins
  • Laundry tubs
  • Washing machines
  • Grey water is not sewerage
  • Grey water makes up 65% of all waste water

Important considerations

  • Grey water systems need to be properly designed and maintained, commercial systems available
  • Due to the source of grey water, it can contain germs that are harmful to human health
  • Grey water can contain chemicals and nutrients (eg phosphorus, sodium) that can be harmful to our environment (depending on the products we use)
  • Use environmentally friendly products

Two types of systems

  • Direct diversion (low cost)
  • Greywater treatment systems

Direct Diversion

  • Greywater diversion devices, allow you to divert your greywater away from the sewer system to your garden
  • You have control over when you want to divert your greywater to your garden or to the sewer

Greywater treatment systems

  • Collect, treat and store grey water to a high standard for reuse
  • Vary greatly in style and cost (more expensive)
  • Can include components such as wetlands, sand filters, soil filters, and aerated wastewater treatment systems

Do I need Council approval for a greywater system?

  • Yes, for a Grey water Treatment device (these treat and store grey water)
  • No, for a Grey water Diversion Device as long as it meets the requirements of 75A of the Local Government Act General Regulation

Requirements for grey water diversion

  • Single dwelling properties only
  • Use a licensed plumber
  • You need to maintain the system so that you prevent odours
  • Prevent contamination of water (back flow prevention)
  • Prevent degradation of soils and vegetation, discourage insects
  • Minimise any adverse impacts on the amenity of the premises and neighbouring land
  • The device must not be used to divert water from a kitchen sink or dishwashing machine
  • You cannot store untreated greywater
  • The greywater must be piped directly to the garden through a sub-soil irrigation system
  • Care must be taken not overload the area with water
  • In wet weather divert greywater to the sewerage system

Other considerations

  • Strathfield Municipality is mainly built on clay based soil which makes absorption of water much slower (need to watch application rate and amount)
  • Laundry products can contain high amounts of phosphorus and sodium, this can be harmful to plants (particularly natives) and soils
  • Please use environmentally friendly products
  • Installing a greywater reuse system can be quite costly
  • Make sure you use the simple low cost water saving options before installing a greywater system
  • Don’t have lots of inefficient appliances and fixtures and rely on grey water alone

For further information please contact Council’s Sustainability Coordinator on 9748 9999.

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