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The Future of Water Supply

The Future of Water Supply

Advice on legislation or legal policy issues contained in this paper is provided for use in parliamentary debate and for related parliamentary purposes. This paper is not professional legal opinion.
Briefing Paper No. 04/2004 by Stewart Smith
Australia, being one of the driest countries on earth, will not be able to escape the pressures of an increasing population and a finite supply of water. Already, Sydney is using 106 percent of the annual sustainable yield of its water supplies. This paper looks at the use of water in Sydney, and the response by water authorities to managing demand. A brief review of water use throughout the State is also presented.

The Sydney Catchment Authority and Sydney Water are the two authorities responsible for the supply of potable water to the Sydney, Illawarra and Blue Mountain areas. The Catchment Authority provides bulk water to Sydney Water, which then retails it to approximately 1.3 million accounts and a population of 4.15 million.

In the Sydney Water service area, the residential sector is the biggest user of water, comprising 61 per cent of total demand. Most of this demand comes from single dwellings, which use an average 825 litres per day, compared to units and apartments which use around 495 litres per day. In regard to residential water use, outdoor water usage is the area of highest consumption (27.3 per cent), followed closely by showers (24.3 per cent).

The safe yield of Sydney’s drinking water storages is 600,000 ML/year. The yield is defined as the amount of water that can be withdrawn from a reservoir on an on-going basis with an acceptably small risk of reducing the reservoir storage to zero. Demand has fluctuated around 600,000 ML/year since 1980, despite population increasing by around 700,000 during this time. Sydney’s water consumption has been above the safe yield for the last three years and for six of the last ten years.

Daily per capita water use has fallen from 506 litres in 1991 to 416 litres in 2002/03. Demand management targets for water conservation purposes were first included in Sydney Water’s 1995 Operating Licence. The current licence has two demand management targets (based on 1990/91 levels). The first is a 2005 target of a 28% reduction in per capita water consumption – 364 litres per capita per day. The second is a 2011 target of a 35% drop in per capita water consumption to 329 litres per day. Sydney Water does not expect the 2005 target to be met.

A review of demand management programs is presented. The most successful demand management programs (in terms of water saved) have been: water recycling at sewerage treatment plants; leakage reduction programs; and the residential retrofit program.

Traditionally, water in urban areas has been supplied through a centralised water reticulation and waste water system. One of the more topical issues in regard to water supply and sewerage infrastructure is that of sustainability and moves towards localised and individual systems. These sustainable approaches and solutions range from simple items, such as rainwater tanks and the better integration of current reticulation systems, to fully independent on-site water systems. Sustainable approaches aim to integrate all elements of urban water services, reducing water use and reusing water wherever possible.