SoE 2003 > Human settlement > 2.2 Urban water

2.2 Urban water

The quality of water supplies is excellent and the main issues now are water consumption and the efficiency of its use

All major urban water systems in NSW provide high quality drinking water that meets the national quality guideline standards. The quality of drinking water in rural and regional areas is less consistent.

Progress is being made on reducing per capita water consumption. However, the high rate of urban population and economic growth, and a need to provide restorative environmental flows in Sydney, mean the pace of reductions will have to increase or additional supply sources will be required.

An integrated approach to urban water management is being pursued to optimise stormwater capture and effluent reuse. This will supplement traditional water supply dams and effluent management.

NSW Indicators

Importance of the issue

There are two dimensions to this issue. The first is the obvious importance of the availability of safe and reliable water services for urban homes and to support economic activity. In general, NSW services consistently meet the applicable national standards in major urban centres. The performance of NSW water supply and sewerage systems against water quality standards are compiled by, and available from, water authorities and NSW Health.

Given the success in achieving excellent drinking water quality in most of NSW, the second and more significant environmental issue is the demand for water placed on the environment by a growing population and economic activity. While approximately 90% of the water taken from the environment in NSW is used for irrigation (NLWRA 2001), urban water use and subsequent effluent discharges in the largest population centres have a profound impact on both the local rivers that supply water and the creeks, rivers and estuaries that receive discharges of treated effluent and urban runoff.

In Greater Sydney, the largest river system, the Hawkesbury–Nepean, has the bulk of its upstream flows regulated by dams, with around 50% of dam inflow diverted from the river to supply the community (AMBS 2000). On the other hand, some of the major downstream tributaries, such as South Creek, receive large steady inflows of treated sewage, whereas previously their natural flows included cycles of drying and wetting. Discharges and overflows from sewage reticulation and urban runoff also affect the quality of receiving waters. While the benefits of secure water supplies are indisputable, the way that major urban communities have historically met their water needs has substantially reduced the ecological health of many river systems.

The Sydney–Wollongong region faces by far the largest urban water challenge, given its absolute size (62% of the NSW population) and rate of population growth (currently more than 50,000 new residents per annum) (see Human Settlement 2.1). 'Yield' is the amount of water that can be withdrawn from a reservoir on an ongoing basis with an acceptably small risk of reducing the reservoir storage to zero. Total water consumption in Sydney has grown to 106% of the yield or 624 gigalitres per annum (Figure 2.2). While this is possible to maintain in the short term, it means that water restrictions will occur more frequently in the future. This, together with the need to increase the amount of water left in rivers for environmental flow, climate change and natural variability, means that there is an urgent need to reduce consumption through such measures as water conservation and recycling.

Figure 2.2: Sydney water consumption versus yield

Source: EPA data, as at June 2003

The current relationship between consumption, yield and the extent of recycling across the major NSW systems is shown in Table 2.2. Water consumption has reached the yield in the Newcastle–lower Hunter region and is estimated to be within the range of yield values for the Gosford–Wyong system.

Water consumption per person per day varies across the systems and is lowest in Gosford–Wyong (estimated at 340 litres per person per day) and highest in other urban systems at an estimated 557 litres per person per day.

Table 2.2: Consumption, yield and recycling across major systems

Sources: ^(a) SCA 2002
^(b) SWC 2002a
^(c) HWC 2002a
^(d) HWC 2002b
^(e) Gosford–Wyong Joint Water Authority at IPART public hearing into metropolitan water pricing: 10 December 2002
^(f) DLWC 2001
^(g) AUWI 2001

Sydney Water Corporation reuses about 2% of total water supplies, approximately 11,000 megalitres (ML) per year or 30 ML per day (SWC 2002a) with most of this used for processing at its sewage treatment plants. The remaining recycled water is used for commercial irrigation and other industrial purposes. Hunter Water Corporation reuses about 4900 ML annually or approximately 9% of the total treated effluent. Most of the effluent is reused for industry (62%) and agriculture (31%).

Outside the greater metropolitan area, about 21% of sewage effluent is reused while the remainder is discharged to waterways. This is an increase on the 12% reuse reported in NSW State of the Environment 2000 (EPA 2000b). The level of effluent reuse around NSW varies according to the availability of surface and groundwater resources and industries requiring water supply. On the coastal fringe, only 2.5% of the total sewage treated is reused. This increases inland with the eastern side of the Great Dividing Range reusing 20% of the sewage treated and the western side of the range reusing 52%. Relative to the total effluent generated, however, reuse remains low in NSW (DLWC data, as at 2002).

Response to the issue

Historically the approach to urban growth has been to increase water supply by building new dams. This increases costs and highlights the limited availability of new raw water sources. In Sydney and NSW generally, current Government policy is to try to reduce demand by increasing water efficiency and reuse before increasing capacity.

Continued upgrade of sewage treatment has been pursued across the State through major investment in sewage treatment plants in urban and regional centres. In the Greater Metropolitan Region alone, capital expenditure for treating wastewater was $379 million in 2001 (IPART 2002b). There has also been considerable investment to reduce discharges from reticulation systems in the larger sewerage systems, including Sydney, Wollongong and Newcastle.

An emerging trend is integrated water cycle management, where the use of recycling, reuse and stormwater capture together will reduce the need for new water supply sources and the impacts of discharges.

Water use and opportunities for conservation

Current data shows that significant progress is being achieved in reducing per capita demand in Sydney (Figure 2.3). Average daily use has fallen from 506 to 412 litres per person per day over the last 11 years. This large improvement reflects the success of considerable and sustained efforts by Sydney Water and the community. However, an additional improvement is required if the targets in Sydney Water's operating licence are to be achieved. These require further reductions to 364 litres per person per day by 2004–05 and 329 litres by 2010–11.

Figure 2.3: Per capita water consumption, Sydney Water

Source: SWC 2002a

Note: Consumption is expressed as litres per day as a 12-month rolling average

The gains to date have been achieved through:

• retro-fitting around 180,000 households with more efficient water devices, saving an average of 20,000 litres of water per household per year
• checking more than 6800 kilometres of Sydney Water's pipes to detect and repair leaks, saving 30.1 million litres of water per day or slightly more than 30 Olympic-sized swimming pools
• partnerships with 105 businesses to undertake audits and develop plans which have identified 12 ML per day of potential water savings with 5 ML per day achieved to date
• mass media campaigns relating to outdoor water use helping to achieve sales of over 4400 water-efficient products (SWC 2002b).

Most urban water is supplied to residential users (Figure 2.4). In turn, the major domestic water uses include outdoor, showering, toilets and laundries (Figure 2.5).

Figure 2.4: Sydney Water customer groups water use, 2001–02

Source: SWC 2002a

Figure 2.5: Typical domestic water use in Sydney

Source: Sydney Water data, as at June 2002

Potable standard water is essential for less than 4% of total consumption, mainly for drinking and personal hygiene (Coombes & Kuczera 2002), yet in Sydney only around 2% of sewage is recycled. This means there is considerable potential for substituting recycled water or captured rainwater for potable water for human use, such as flushing the toilet and watering the garden. Depending on densities and rainfall, domestic rainwater tanks of between 5000 and 15,000 litres could reduce mains consumption by 85% and use up to 90% of the stormwater falling on collection surfaces (Coombes & Kuczera 2002). Sydney Water and some other supply authorities have been offering householders cash incentives to install rainwater tanks and connect them for garden and appropriate internal use.

Changes in water use behaviour and more efficient fittings and appliances are also key strategies for conservation. These can be achieved through public education, revising price structures, water restrictions, new standards and retro-fit programs. Most major supply authorities in NSW are pursuing a combination of these approaches.

Urban water discharge

Approximately 70% of water piped into urban areas is returned via sewerage systems to sewage treatment plants. Following treatment, almost all is discharged to creeks, rivers, estuaries or the ocean. There have been substantial reductions in the pollutant loads of many discharges to rivers and estuaries in recent decades, while the impacts of most ocean discharges on beaches have been largely addressed by constructing extended ocean outfalls (see Water 5.6).

Overflows from sewage reticulation systems continue to have a significant environmental impact in urban areas. Dry-weather discharges are usually due to chokes caused by tree roots or breakages, while infiltration of stormwater through breaks and illegal connections contribute to wet-weather overflows.

Sydney Water has embarked on a 20-year program of sewage overflow abatement works to reduce the impact of dry- and wet-weather discharges to the environment. The $2-billion program aims to eliminate 80–90% of wet-weather sewage overflows across Sydney (SWC 2002c). The most recent data (Table 2.3) shows that the number of overflows in Sydney has remained relatively stable in recent years.

Table 2.3: Overflows from the Sydney Water sewerage system

Source: SWC 2002a

Outside Sydney, service providers in large regional centres also have active overflow reduction programs, while the operators of smaller systems are being progressively required by the EPA to assess risks in order to develop remediation plans.

Effectiveness of responses

NSW Health receives and compiles information on the quality of drinking water in NSW. The Department's Drinking Water Monitoring Program and database show consistently high quality water is supplied in large urban centres, although in smaller inland settlements quality is more patchy.

Significant progress has been made in reducing demand for potable water in the largest urban areas, which is where the greatest effort is required. However, this work will need to be intensified across agencies, industry and the community to provide for anticipated population and economic growth and achieve the necessary environmental flows in major urban river systems.

The beginning of the move to integrated water cycle management in urban areas in NSW is timely although challenging. NSW is progressing as quickly as other comparable places.

Future directions

A combination of behavioural, structural and economic changes will most effectively reduce water demand.

For householders, there is a wide range of water conservation measures. Sydney Water and Sydney Catchment Authority have details of these, which include changes in patterns of use, fittings and more efficient appliances. In some cases, financial incentives are available to assist with implementation.

Industry and other large water users can also conserve water with these approaches; some may also be able to use recycled water instead of potable or river supply.

Government agencies can continue to support the community in its efforts through intensifying attention on the pricing of different grades of water; streamlining regulatory requirements, such as facilitating substitution of potable or river water with recycled water; and supporting effective integration of water services. A key challenge will be facilitating innovative water technologies that reduce the need for reticulated supply and better protect local environments.

Linked issues

2.1 Population and settlement patterns

5.2 Surface water extraction

5.3 Surface water quality

5.6 Marine and estuarine water quality