Over 70 % of water used in Australian urban households does not need to be potable.
You are planning a new estate and you want it to be water efficient. A recycled water main is nearby and can be extended into the estate. A pipe with potable water will pass every lot, but how to make a network of pipes for recycled water stack up? Can rainwater tanks do the job instead?
This bulletin explores the options for water infrastructure in residential estates, and how design standards can help achieve efficient and attractive water infrastructure.
Average household water use, by Australian states. [For the sources for each state, see: Victoria, South Australia, New South Wales, Western Australia, Queensland.]
Types of urban water
Houses in urban Australia have three potential sources of water: potable water, recycled water, and rainwater. These are detailed below.
Potable water
Potable water is clean water suitable for all uses, including drinking and bathing. It is often obtained from dedicated water catchments. All urban areas in Australia have a piped supply of potable water.
Although potable water is typically used in all areas of the house and yards, other types of water can be used where drinking quality water is not required.
Recycled Water
Recycled water is water that has been treated to make it suitable to use in washing machines, toilets, and gardens. It is not suitable for drinking or bathing. Pipes and fittings used for recycled water are usually coloured purple. Recycled water typically costs less per litre in urban areas than potable water.
Connection of a residential estate to a recycled water supply may be required if a recycled water plant or pipeline is nearby. Installing a network of pipes for recycled water throughout an estate will cost an estate developer money. While every urban lot will be connected to a potable water system, connection to a recycled water system may be voluntary or mandatory.
Recycled water taps and pipes are coloured purple to clearly distinguish the water from drinking water.
In a front yard, meters and taps for recycled water are often quite prominent. Requiring meters to be placed in boxes or behind shrubs, and placing the taps on the side walls of houses, can make them less conspicuous and the streetscape more attractive.
Purpose-built containers above or below ground makes taps and meters less prominent.
Rainwater
Rainwater can be collected from roofs and stored in tanks for later use. Almost all Australian houses already have gutters collecting the rainwater running off roofs. From the gutters, it's usually piped straight into the public storm water system.
As rainwater is collected from roofs, it may contain contaminants, such as possum droppings. As free second-quality water, it can be used in the laundry, garden and toilets. The use of rainwater tanks can reduce the demand for potable and recycled water, as well as the demand on the storm water system.
This rainwater tank is close in colour to the house; this reduces its prominence.
Design standards
A second water supply reduces demand for potable water. If recycled water is available in the estate, it makes sense to make it mandatory. If recycled water is not available, rainwater tanks are a good option. Some design codes require lot owners to connect to recycled water and to install rainwater tanks!
Below are some recommended design standards relating to water infrastructure.
A connection to a second water supply may be mandated.
“The house must be connected to the purple pipe recycled water supply.”
A second-quality water source can reduce the demand for potable water.
“The rainwater tank must be plumbed for outdoor areas, laundry and toilet use.”
A rainwater tank can reduce demand on the stormwater system.
“A rainwater storage tank must be installed with a capacity of at least 2,500 litres.”
Meters, taps, tanks and downpipes can be prominent if visible from the public realm. A design standard can reduce their prominence.
“Rainwater tanks must be coloured to match the house and be located away from direct public view.”
“Taps and meters for potable and recycled water must be located in garden beds and not be prominent when viewed from the street.”
