Greywater Reuse

What it is

Greywater is wastewater from hand basins, showers, spas, washing machines, laundries, and kitchen sinks and dishwashers (and not from the toilet or urinal - which is Blackwater). The reuse of greywater varies from bucketing or siphoning, connecting the outlet drain to a diversion pipe or installing an appropriate greywater treatment system.

What we are currently doing

Greywater reuse is a major component of the ACT Government's Think water, act water strategy, which includes a target to increase reclaimed water from 5% to 20% by 2013. The strategy is continuing to investigate ways to encourage the take-up of greywater use with consideration given to incentives and rebate schemes.

It is also factored into the ACT Government’s Water Sensitive Urban Design (WSUD) guidelines. The WSUD target for all new developments and re-developments is a 40% reduction in drinking water use.

Greywater use can replace some drinking water use and contributes to water conservation measures. In addition it also reduces sewerage flows, which reduces treatment costs and discharge volumes to waterways. Due to poor water quality however, untreated greywater should only be used for irrigation and cannot be stored for more than 24 hours unless an appropriate treatment system is used (as per ACT Health requirements). Treated greywater can be used for other purposes.

Issues

For the 65 gigalitres per year total average Canberra consumption, the greywater potential is about 11.6 gigalitres.

Think water, act water states greywater costs approximately $5 per kilolitre, noting this cost is for rebates only (cost to government). The highest current cost of drinking water in the ACT is $1.74 per kilolitre plus the ACT Government's $0.55 kilolitre Water Abstraction Charge.

The installation of a sophisticated greywater system has been estimated at $10,000 - $15,000 per household. For the ACT's 110,000 properties, it is estimated the proposal would cost in the region of $1.1 billion to $1.6 billion, producing about 12 gigalitres per year.

This cost would be met up front by today's generation (assuming the property owner or ACT Government did not borrow to fund the works).

The time required to implement these greywater systems in all households, would be many years. This is largely due to the limited supply of greywater systems, limited availability of plumbers and drainers for installation, and the logistics of fitting systems to 110,000 properties.

Greywater systems need to be continually managed including ongoing monitoring and regular maintenance, otherwise health and garden issues can arise.