Blue Mountains City Council

Grey water Diversion Devices
Grey Water Diversion Devices

marked with a 'Watermark' license do not require the prior Approval of Council to install, however, those devices not in possession of such a watermark will require formal Council Approval.

Downloads




 

Grey Water

"Grey Water" refers to any waste water that is not classified specifically as "Black Water", and encompasses water from washing machines, dishwashers and showers/bathtubs.

Grey Water does not include any waste waters from toilets or bidets as these are classified as "Black Water" and will contain a significant amount of pathogens that can have a marked effect on both human and environmental health. This is due to the fact that grey Water will comprise in excess of 50% of a household's wastewater from sanitisation practices, excluding toilets/bidets.

While grey water may not be the waste water from toilets/bidets, it still has the potential to harbour pathogens, and may contain a large amount of nutrient (from detergents and soaps) thus will still need to be used with care.

Grey water is to be piped in specifically coloured Lilac irrigation piping to show the source and content of the recycled waters.

There are generally two types of grey water re-use systems:

  • Grey water Diversion Devices (GDD) - These are simply put, systems which divert grey waters directly from waste water devices (such as washing machines) to a sub-surface disposal system. No storage of the diverted grey water is allowed, and the grey water must be disposed of at least 100mm below the natural ground surface.
    GDD that have been marked with a "Watermark" license do not require the prior Approval of Council to install, however, those GDD not in possession of such a watermark will require formal Council Approval.
  • Domestic Grey water Treatment Systems (DGTS): These systems are more complex than general GDD, and allow for a specific treatment of grey waters prior to usage or storage. A DGTS will treat grey waters to a level for acceptable re-use in toilet flushing, use as washing water (in washing machines), car washing and surface disposal around the garden. Unlike GDD the grey water treated in a DGTS may also be stored appropriately for later re-use.
    DGTS are all very specific in their use and function, and should be thoroughly researched prior to potential use on your property.
    Regardless of the type, the system must have a 'Certificate of Accreditation' issued from the Department of NSW Health.
    NB: Council will not approve a system for use that is not in receipt of such an accreditation certificate.
    A current list of accredited DGTS can be viewed on the Department's website: www.health.nsw.gov.au

Please note - Grey water is not allowed to be stored unless it has first been treated to an acceptable level.
Additionally, grey water should only be used for garden irrigation in the same quantities normal potable (tap) water would be. Excessive usage can lead to salinisation of soils and a build up of nutrients in the underlying water table.

The Department of NSW Health document on "Grey water reuse in sewered single domestic premises" may be downloaded at right.

Grey Water re-use should NOT be used in environmentally sensitive areas, such as escarpments and in areas comprised of sensitive vegetation, or in proximity to waterways. If you have any reservations about Grey Water re-use, please contact one of Council's Environmental Health Officers on (02) 4780 5000.

Further information relating to groundwater can be found at the following Government Department websites: