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Recycled water systems can operate at a number of scales, as outlined below.

• Household: Onsite treatment, storage and reuse of recycled water
• Neighbourhood: Collection of wastewater at individual households, treatment and storage at shared neighbourhood facility, with households serviced by dual pipe system that collects wastewater and returns treated water for non-drinking uses. Sewer mining is another source of recycled water for neighbourhoods, which involves tapping directly into a proximal sewer main and extracting and treating wastewater for non-drinking uses, with sewer mining by-products returned to the sewerage system
• Centralised: Wastewater is reclaimed from large–scale wastewater treatment plants servicing the greater region; reclaimed wastewater is treated to a high, Class A standard and then pumped to the development where it is distributed to individual households by a third pipe reticulation network.

Figure 1 - Conventional drinking water supply system (WSAA, 2006 p. 8)

The traditional approach to wastewater services takes a ‘once through’ approach, where high quality water is used once then discharged for treatment and discharge to receiving waters (See Figure 1). However there is the potential to take water from the wastewater system and treat it to a suitable quality for use in a range of purposes. Recycled water offers the opportunity to ’close the loop’ of water use, as it allows for multiple reuse of water supplied to residential developments (See Figure 2).

Figure 2 Water recycling for non-drinking uses (WSAA, 2006 p. 8)

 

Overview

This fact sheet will only consider the application of recycled water for non-drinking related purposes. Numerous Australian studies have shown that communities generally have positive attitudes to recycling water for non-drinking purposes, but there are low levels of support for the use of recycled water for drinking purposes (NRMMC, 2006). Planned indirect water recycling for drinking purposes, where recycled water is added to the water supply system, is still yet to receive broad public approval and is currently beyond the scope of a single development, particularly in an urban context.
The fact sheet focuses on wastewater recycling systems for multiple dwellings. Wastewater is defined as all water (excluding direct stormwater runoff) leaving a dwelling and can be classified into blackwater and greywater.

• Blackwater: Contains waste from the toilet, therefore, typically has a high load of pathogens and nutrients and requires advanced levels of treatment to render it useable.
• Greywater: Greywater is any wastewater from a property apart from toilets (Diaper, 2004). Most greywater recycling focuses on bathroom and laundry discharged water only, due to the high concentration of fats, food particles and detergents from kitchen wastewater. Guidelines generally require greywater stored for more than 24 hours to be treated to avoid odours.

Stormwater is another source of recycled water. The potential use of stormwater is covered in a related fact sheet.
A key concept when considering opportunities for recycled water is fit for purpose. This philosophy for providing water services considers the quality required by the end use and matches this with an appropriate water source. This approach avoids using high quality drinking water for uses where lower quality recycled water would suffice.
Treatment technology for recycling water can be based on chemical, biological or physical processes, or a combination of these (Diaper et al, 2007). The selection of appropriate technology will be influenced by source of wastewater, site characteristics, scale of development, intended applications of recycled water and regulatory requirements (Landcom, 2006).

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Case Study – Rouse Hill residential recycling scheme

Rouse Hill residential recycling scheme in Sydney’s north-west is Australia’s largest water recycling scheme. The scheme incorporates a dual reticulation where recycled water sourced from treated wastewater is supplied for non-drinking uses, such as flushing toilets, watering gardens and car washing.

The Rouse Hill recycling scheme provides 1,900,000 kL a year for non-drinking uses to 16,500 homes, which represents a saving of approximately 115 kL per year for each household (Sydney Water, 2007).

The cost of recycled water is priced at $0.71 /kL (drinking water is priced at $0.98/kL) while the cost of providing the recycled water is estimated at $3-4/kL (ASTE, 2004).

The main issue faced at Rouse Hill in the commissioning and ongoing operation of the scheme has been the reliability of plumbing work undertaken by private contractors, between the Sydney water main and house fittings (ASTE, 2004). An audit prior to the commissioning of the system revealed approximately 50 direct cross-connection and numerous other plumbing faults that needed to be rectified. Despite a concerted effort to educate plumbers, there have been four post-commissioning incidents of cross-connections due to faulty household plumbing (NRMMC, 2006).

The scheme was initially developed as part of an integrated urban water management program to minimise the impact of new residential development on environmentally sensitive receiving waters, in particular the Hawkesbury River.

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Case Study – New Haven Estate

New Haven estate is located about 18 kilometres from Adelaide. This medium density development of 62 houses incorporates a decentralised sewerage treatment system and dual pipe water recycling system for irrigation and toilet flushing use. At the time of its development in 1995 it was the first development in Australia to use recycled water for toilet flushing.

The tertiary wastewater treatment system uses activated sludge, sand filtration and ultraviolet disinfection to treat wastewater before it is returned to households for garden irrigation and toilet flushing.

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Key Issues

Benefits

There are a number of recognised benefits from implementing a recycled water scheme. These include:

• Reduced pressure on drinking water supplies from non-drinking related uses, where water quality is less important and substitution with recycled water would be adequate (Dimitriadis, 2005). In residential areas approximately 70% of water supplied, is used for non-drinking uses that demonstrate the potential impact that substitution with recycled water can have in reducing demand for drinking water.
• Reduced stress on surface water catchments and groundwater aquifers, and increasing environmental flows to rivers and for wetlands maintenance (Foley et al, 2007)
• Recycled water provides a largely rainfall-independent supply of water to residential areas. Australia's extended period of drought and projected impact of climate change on rainfall reliability highlights the need to consider both demand management and alternative sources of water supply
• Improve water supply security for non-drinking purposes, such as garden irrigation
• Water recycling can significantly reduce the quantity of wastewater discharged to receiving waters, such as rivers and the ocean
• Reduced pressure on capacity of centralised water and wastewater infrastructure, such as treatment facilities and pipe networks.

Read about how the Aurora development uses recycled water, to create significant water savings.

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Risks

Sources of recycled water can potentially contain pathogens, nutrients and chemicals that pose a risk to human health and the environment. There is a need to manage the health risks associated with use of recycled water.

A cross-connection is defined as any point in the plumbing system where it is possible for non-drinking water sources to contaminate drinking water supplies. The risk of cross-connections needs to be managed through preventative measures. It has been shown that most cross-connections occur beyond the service connection, within the residential plumbing system (US EPA, 2001).

The following measures mitigate the health risks associated with recycled water use:

• Education of householders to ensure appropriate use of recycled water
• Education of plumbers
• Appliances and pipes should be clearly identifiable using purple assets and labels that indicate recycled water is in use
• Cross-connection controls and backflow prevention devices/measures should be implemented where appropriate and
• All pipe-work should be installed in adherence to Australian Standard (AS)/New Zealand Standard (NZS) 3500 (Plumbing and Drainage Code, AS/NZS 2003), Water Services Association of Australia (WSAA) Water Supply Code (WSAA 2002) and WSAA Dual Water Supply Systems, Version 1.2 (WSAA, 2005).

In commissioning and operating a recycled water scheme it is essential to protect the health of the public and the environment. An incident where recycled water comes into contact with drinking water supplies is likely to reduce residents' confidence in the scheme.

Standard treatment processes mostly focus on removal of pathogens to reduce risks to human health, while some chemicals of environmental significance are not significantly reduced in many treatment processes. The risk posed to the environment depends on the source of the recycled water, its intended use and the final receiving environment (NRMMC, 2006). Potential recycled water contaminants that pose a risk to the environment include nitrates, phosphates, boron and total dissolved solids.

Another risk is the potential for insufficient demand for recycled water.

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Savings

The substitution of recycled water for non-drinking uses results in significant savings of high quality drinking water. The chart below provides a breakdown of end use demand for Australian households, which shows the potential uses for recycled water (toilet, garden and laundry) represent almost 70% of total average demand of 193 kL for each household a year.

In most cases residents will save money by shifting to recycled water for non-drinking uses.  Recycled water around the world is generally not priced for full cost recovery, but to provide an incentive for use of recycled water (ASTE, 2004).   A paradox faced in pricing recycled water is that setting the price on parity to drinking water may encourage residents to err on the side of caution and favour drinking water for non-drinking uses, while pricing recycled water too low relative to drinking water may encourage inefficient use.  In Mawson Lakes recycled water scheme in South Australia, the cost of recycled water has been set at 75% of the cost of drinking water, which is expected to save the average household approximately $30 a year. 

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Costs

Use life cycle costing to assess the relative costs of different water recycling schemes. This approach also enables comparison with traditional approaches to providing water and wastewater services.
The cost of a recycled water scheme will be significantly influenced by the location of wastewater sources and proximity to existing services. If the source of the recycled water is distant, then the capital cost of a dual pipe network to transport the recycled water may be prohibitive. However, if new development is not easily connected to existing centralised water services this may increase the economic feasibility of alternative water sources, such as recycled water.
Consideration of the costs of a water recycling scheme compared to a traditional water servicing approach needs to take into consideration externalities, such as environmental impact and social aspects. Generally, for developments proximate to existing services, the cost to install and operate a dual pipe system for recycled water will cost more than conventional water servicing. However, take into consideration the reduced loads on centralised infrastructure and reduced environmental impact from wastewater discharge. Recycled water schemes have the potential to defer or avoid costs associated with maintaining or increasing the capacity of centralised systems.

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Barriers

Community attitudes: generally there is high community acceptance of recycled water use that does not involve close personal contact (Landcom, 2006). Recent surveys have shown that less than 5% of respondents are opposed to the use of recycled water for garden irrigation or toilet flushing (Rathjen et al, cited in ATSE 2004).

Community members, while benefiting from a recycled water scheme, will also bear much of the associated costs and risks, therefore, they need to have access to relevant information and be involved in the decision-making process.

Ongoing maintenance and ownership: Resolve who takes ownership of the recycled water after it is commissioned and/or who will take responsibility for ongoing maintenance to ensure reliability of system. There are four main models for managing and operating local recycled water schemes (Landcom, 2006):

• Local regulatory body such as the water utility or local government,
• A body corporate owns and operates the system,
• A private company owns the systems and leases the services, and
• Hybrids of the above. For example, owned by a body corporate and operated by a water utility.

Costs: As discussed previously the cost of commissioning and operating a recycled water scheme can initially appear prohibitive, however, when externalities, such as environmental impact, are fully costed, as is provided for under Council of Australian Governments (CoAG) water reform principles, costs are more likely to be comparable with conventional water services (ASTE, 2004). The costs associated with validating a recycled water scheme during commissioning and ongoing monitoring can also represent a potential barrier to small decentralised schemes.

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Benchmarks

The regulatory requirements and guidelines for recycled water use differ between different States, and also vary depending on the source of recycled water and nature of use. The required benchmarks for a recycled water scheme need to be considered within the regulatory framework of the relevant State government departments, local Councils and water authorities.

Individual state guidelines on the use of recycled water and greywater include:

• South Australian Reclaimed Water Guidelines – Treated Effluent (DHS, 1999),
• Guidelines for Environmental Management: Use of Reclaimed Water (EPA Victoria, 2003), and
• Code of Practice for the Reuse of Greywater in Western Australia (Department of Health – WA, 2005).

A 12 step risk management framework for recycled water quality and use is detailed in Australian Guidelines for Water Recycling: Managing Health and Environment Risks (NRMMC, 2006).

Standards and guidelines for dual pipe systems are incorporated in: AS/NZS 3500 (Plumbing and Drainage Code, AS/NZS 2003), WSAA Water Supply Code (WSAA 2002) and WSAA Dual Water Supply Systems, Version 1.2 (WSAA, 2005).

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Development phase actions

Feasibility

The initial feasibility assessment of opportunities for recycling water should focus on understanding the local conditions to identify feasible options for providing recycled water services. It is not cost effective to analyse every potential recycled water option in detail, so it is important in this phase that all potentially suitable options are screened to identify those showing most promise. These can then be analysed in greater detail.
Screening of feasible options should consider:

• Sources: Identify and characterise potential sources of recycled water to determine potential for supplementing drinking water supply. Consider proximity to sewer mains and wastewater treatment plants.
• Demand: Identify and characterise the likely demand of the residential development, both in terms of quality and quantity required for different end-uses.
• Development characteristics: The scale and type of development will influence feasibility of alternatives for recycled water use. Factors to consider include; dwelling density, number of residents, area requiring irrigation, climate and soil (for estimating irrigation requirements), topography and space available for treatment and storage.
• Reliability of supply: Identify the ability of different sources of recycled water to meet the required demand.

After the initial screening a more detailed assessment of recycled water options should consider:

• Life cycle costing: Undertake a life cycle costing analysis for all water recycling options to enable comparison of costs over the scheme’s life time.
• Skills and knowledge: Consider the availability of skills and knowledge that will be required to operate and maintain the recycled water scheme.
• Social acceptability: The public acceptability of the scheme is critical to its success
• Health risks: Consider the inherent health risks in different water recycling options.
• Environmental constraints and impact: Identify environmental constraints or potential impacts from implementing different recycled water schemes. The environmental risks faced will be specific to the site, source of recycled water and likely uses.
• Management and operational structure: Identify the most appropriate ownership and operational structure, consistent with the type of development and the operating regime.

Key Output
Identification of a preferred feasible option for the delivery of recycled water services to the development. This will be based on site specific opportunities and limitations.

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Planning

The preferred option from the previous stage is now assessed in greater detail in order to develop a plan for commissioning the recycled water scheme. Consider the following in development of a plan:

• Sources of funding: are there any potential sources of funding to offset costs of a recycled water scheme?
• Legislative and regulatory requirements: Determine the impact of existing and proposed legislative and regulatory frameworks
• Establish partnerships: Local, state and federal government agencies will need to be involved to review and approve the recycled water scheme. Develop a strong relationship with water utilities, as it is likely they will be involved in delivering and/or operating the scheme. The scheme needs to be taken into consideration by the utility in planning centralised water and wastewater services for the new development
• Ownership and management: Develop a plan for the ongoing operation and maintenance of the recycled water scheme.
• Stakeholder involvement and communication strategy: It is important that the process of commissioning a recycled water scheme is open, informative and transparent.
• Integrated urban water management: Identify how the water recycling scheme integrates with other aspects of water resources planning, such as stormwater management.
• Health risks: Undertake a risk assessment of the preferred scheme and plan preventive measures to reduce risk to an acceptable level
• Environmental impact: Undertake environmental risk assessment of the preferred recycled water scheme and develop plan for management of environmental risks identified.
• Technology selection: Select appropriate technology to deliver the recycled water scheme. In addition to technical viability and economic cost benefit analysis, the following criteria should also be considered in the selection process; water end use and demand profile, water quality and treatment, interaction with existing infrastructure, space required, social acceptability, monitoring, operation and maintenance requirements, ownership, and health and environmental risks (Landcom, 2006).

Key Output
A detailed plan for the delivery of recycled water scheme. The plan should consider and address environmental and human health risks.

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Design

The formal design process needs to consider the following

• Demand: Design the system on the basis of estimated end use demand for non-drinking water identified in the feasibility phase. Determine which system, recycled or drinking water, will provide fire fighting capacity
• Storage and reliability: Design should assess storage volume required to cope with any seasonal fluctuations in supply or demand, while still maintaining acceptable reliability and quality of supply
• Allowable service pressure: The non-drinking water supply system should be designed with lower pressure than drinking water supplies to prevent contamination by backflow in the event of cross-connection
• Landscape amenity:  Aspects such as the storage facilities can be an important landscape feature. The design of the recycled water scheme should be integrated with the overall masterplan for the development
• Standards: System should be designed in adherence to AS/NZS 3500 (Plumbing and Drainage Code, AS/NZS 2003), WSAA Water Supply Code (WSAA 2002) and WSAA Dual Water Supply Systems, Version 1.2 (WSAA, 2005)
• Guidelines and Regulations: Design systems in accordance with relevant government guidelines and regulations for recycled water use.

Key Output
Design of the recycled water scheme that is integrated with all other aspects of the overall masterplan for the development, such as land use, environmental performance, stormwater management and landscape

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Construction

• Identification: Recycled water supply systems must be clearly differentiated from drinking water supply. This includes installing markers that identify the system as non-drinking water supply; eg non-drinking water supply pipes coloured purple. Appliances, such as garden taps, using non-drinking water supply should have an advisory sign warning against consumption
• Location of mains: The location of non-drinking water mains relative to drinking water supply should be in accordance with WSAA Dual Water Supply Systems, Version 1.2 (WSAA, 2005) and the requirements of local water authority.
• Validation of system: Prior to residents moving into the estate and using the recycled water, validate the system. This may include challenge testing where the input to the treatment system is spiked with cultured organisms and the treated water monitored to determine the performance of system in reducing pathogens.

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Lot Creation

• Householder education: Incoming residents need to be aware of the appropriate uses for recycled water. Education, both initial and ongoing, is essential
• Plumber education: All plumbing work should be carried out by a licensed plumber. Educate plumbers about the risk of cross-connections.

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Completion

A number of ongoing actions are required to ensure the sustainability of a water recycling scheme:

• Audits: Random auditing of plumbing works may be carried out to identify any defective pipework that may lead to cross-connections
• Demand management: There is a need to conserve recycled water as for drinking water. Recycled water is a high quality resource that requires significant energy to treat and transport. Minimising demand through strategies such as efficient appliances ensures a cost-effective and sustainable approach to recycled water use
• Monitoring: Ongoing monitoring of the scheme is needed to ensure that it is performing as intended.
   

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ASTE (Australian Academy of Technological Sciences and Engineering) (2004). Water Recycling in Australia.  Victoria, Australia.  Available at: http://www.atse.org.au/index.php?sectionid=600

Department of Health – WA (2005) Code of Practice for the Reuse of Greywater in Western Australia, Department of Health – Western Australia. Available at: http://www.health.wa.gov.au/envirohealth/water/greywater.cfm

Department of Sustainability and Environment (2005) Victoria in Future 2004. The Victorian Government Department of Sustainability and Environment. Available at: http://www.dse.vic.gov.au/DSE/dsenres.nsf/LinkView/8B232276A311D5F1CA256EF6001BCFE706C7DF80826B65674A256DEA002C0DCA

DHS (Department of Human Services) (1999) South Australian Reclaimed Water Guidelines – Treated Effluent, Department of Human Services and Environment Protection Agency – Government of South Australia. Available at: http://www.epa.sa.gov.au/pdfs/reclaimed.pdf

Diaper, C. (2004) Innovation in on-site domestic water management systems in Australia: A review of rainwater, greywater, stormwater and wastewater utilisation techniques. Australian Water Conservation and Reuse Research Program, CSIRO Urban Water Technical Report 2004-073. Available at: http://www.clw.csiro.au/awcrrp/stage1files/AWCRRP_5_Final_28Apr2004.pdf  

Diaper, C., Tjandraatmadja, G. and Kenway, S. (2007) Sustainable Subdivisions: Review of technologies for integrated water services.  Cooperative Research Centre for Construction Innovation.  Available at: http://www.construction-innovation.info/index.php?id=1034

Dimitriadis, S. (2005) Issues encountered in advancing Australia’s water recycling schemes, Parliament of Australia – Science, Technology, Environment and Resources Section Research Brief no. 2 2005-06. Available at: http://www.aph.gov.au/library/pubs/rb/2005-06/06rb02.htm

EPA Victoria (2003) Guidelines for Environmental Management: Use of Reclaimed Water, Environment Protection Agency – Victoria. Available at: http://epanote2.epa.vic.gov.au/EPA%5Cpublications.nsf/PubDocsLU/464.2?OpenDocument

Foley, J., Batstone, D. and Keller, J. (2007) The Challenges of Water Recycling – Technical and Environmental Horizons. Advanced wastewater Management Centre, The University of Queensland.  Available at: http://www.awmc.uq.edu.au/docs/water_recycling_pospaper_short.pdf

Landcom (2006) Wastewater reuse in the Urban Environment: selection of technologies.  Report prepared by Ecological Engineering for Landcom. Available at: http://www.landcom.com.au/Wastewaterreuse.aspx

NRMMC (Natural Resource Management Ministerial Council) (2006). National Guidelines for Water Recycling: Managing Health and Environmental Risks, Natural Resource Management Ministerial Council, Environment Protection and Heritage Council and Australian Health Ministers’ Conference. Available at: http://www.ephc.gov.au/ephc/water_recycling.html

Sydney Water (2007) Rouse Hill Recycled Water Scheme.  Accessed 08 January 2008 at: http://www.sydneywater.com.au/SavingWater/RecyclingandReuse/RecyclingAndReuseInAction/RouseHill.cfm

US EPA (United States Environmental Protection Authority) (2001). Possible contamination due to cross-connections and backflow and the associated health risks.  US EPA - Office of Groundwater and Water Distribution System Issue Paper. Available at: http://www.epa.gov/ogwdw/disinfection/tcr/pdfs/issuepaper_tcr_crossconnection-backflow.pdf

WSAA (Water Services Association of Australia) (2002) Water Supply Code of Australia, WSAA, Melbourne. 

WSAA (2005). Dual Water Supply Systems, Version 1.2, WSAA, Melbourne. Available at: https://www.wsaa.asn.au/frameset2.html

WSAA (2006) Refilling the Glass: Exploring the issues surrounding water recycling in Australia, WSAA Position Paper No. 02.  Available at: http://www.amwa.net/galleries/climate-change/WSAAPositionPaper2%20Refilling%20the%20Glass.pdf