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Rainwater Harvesting and Greywater Re-use Systems

The introduction of BASIX into the development approval process requires new housing in NSW to be designed and built to use 40% less drinking water than average NSW homes of the same type.

A typical development will meet the target for water conservation if it includes:

  • showerheads and tap fittings with at least a 3A rating;
  • dual flush toilets; and
  • a rainwater tank or equivalent communal system of a minimum specified volume, or a connection to an appropriate recycled water supply for outdoor water use and toilet flushing and/or laundry.

Simply put, most new housing in NSW will require a rainwater tank supply for outdoor water use, toilet flushing and/or laundry. Multi-unit developments will be more complex and may require greywater treatment and re-use systems.

So where do you start? There are a multitude of considerations and informed decisions that must be made when choosing a rainwater harvesting system. Where should you locate the tank? Do I need a leaf and debris diversion system? Should I install a First Flush Water Diverter? What type and size of tank or storage system? What does it need to be connected to and do you require a pump?

Basix Environmental Solutions offer advisory and design services for effective Rainwater Harvesting and Greywater re-use systems.

The rainwater harvesting services we offer include:

  • Sizing and selection of rainwater storage tanks;
  • Design of your rainwater harvesting system, within local Water Authority regulations (which differ from place to place);
  • Innovative, space saving, and value adding design solutions for small sites; eg. tanks as a fence, along a wall, under a floor, in the backyard, as a shed. Your imagination is the limit.
  • Lot level water balances and rainwater tank modelling for precise performance information;
  • Referrals to reliable installation contractors in your area;
  • Advice on how to best manage and conserve water.

The more internal fixtures (like toilets and washing machines) connected to your rainwater tank, the more water you can save, and the easier it will be to comply with BASIX requirements, but this needs to be organised early in the building process to enable the plumbing connections to be fitted.

By installing a rainwater tank, connected to a drip irrigation system and mulch, you can continue to water in an efficient and effective manner, and maintain a healthy garden. Many local water authorities and councils are offering rebates of up to $1200 for the installation of rainwater tank systems - contact us for more information.

Greywater Reuse Systems

Greywater is defined as the wastewater generated by the washing machine, shower/bath, and taps in the bathroom, kitchen and laundry. Kitchen wastewater however is not recommended for untreated re-use as it can contain large amounts of food waste, oils and grease.

Reuse of greywater can provide a constant source of water to keep your garden healthy, and it can assist you comply with BASIX requirements, allowing compromises in meeting the 40% water conservation target (such as a smaller size rain tank to be chosen, or negate the need to install a raintank). But the systems need to be installed and used correctly, and there are limitations on what the water can be safely used for.

For instance, a greywater diversion system that irrigates the garden may add around 11% towards the 40% target, or a treated greywater system may add 14%. If a treated greywater system was used for toilet, laundry and garden it could add 35% towards the target!

Basix Environmental Solutions offer advisory and design services for Greywater diversion systems. Government requirements around greywater reuse are in a major state of flux at the moment so contact us for advice.

The Greywater reuse services we offer include:

  • Selection of Greywater diversion systems;
  • Design of Greywater diversion systems, and assistance with obtaining Council approval;
  • Greywater system modelling for performance information;
  • Referrals to reliable installation contractors in your area;
  • Advice on how to best manage greywater.

The two types of greywater reuse systems are referred to as Diversion Systems or Treatment Systems

Diversion Systems

Greywater diversion devices (GDD) do not treat the greywater but divert it from the source to another use. Untreated greywater should only be diverted from the laundry, shower and bath, and must only be used with a subsurface irrigation system to minimise human contact. A direct diversion system is not permitted to store greywater, any greywater not used must be returned to the sewer via a gully or trap.

Treatment Systems

A greywater treatment system (GTS) involves the collection, storage, treatment and possible disinfection of greywater to the standards specified by NSW Health. Where the water quality meets NSW Health’s requirements it may be used for toilet-flushing and laundry use. Unfortunately, however, at present no domestic greywater treatment systems are approved by NSW Health (as at October 2004), so this is not really an option for most urban lots. This type of greywater reuse can be quite expensive and is more suitable for communal systems (eg. a multi-unit development), or for more rural sites.

For more information go to www.basix.nsw.gov.au or www.health.nsw.gov.au

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