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Australian Guidelines for Water Recycling

Australian Guidelines for Water Recycling Phase 1

The Australian Guidelines for Water Recycling (Phase 1) were released in November 2006 after three years of collaboration between the Natural Resource Management Ministerial Council and the Australian Health Ministers Conference. These guidelines were developed due to the growing pressure on Australia’s water resources and the need to increase water recycling in order to cope with both current and future demands.  Phase one has been endorsed (approved) by the Environment Protection and Heritage Council, the Natural Resource Management Ministerial Council and the Australian Health Ministers' Conference.  Phase one focuses on:

  • large-scale treated sewage and grey-water reuse;
  • residential garden watering, car washing, toilet flushing and clothes washing;
  • irrigation for urban recreational and open space, and agriculture and horticulture;
  • fire protection and fire fighting systems;
  • industrial uses, including cooling water; and
  • greywater treated on-site (including in high rise apartments and office blocks) for use for garden watering, car washing, toilet flushing and clothes washing.

The guidelines include a risk management framework and specific guidance on how to manage the health and the environmental risks associated with the use of recycled water.  There is also a report called National Guidelines for Water Recycling – Managing Health and Environmental Risks – Impact Assessment which assesses the possible impacts of increased water recycling and reuse on a national level.  This new guideline is a great improvement to previous ones as it provides greater flexibility and modernisation in its strategies and encourages water recycling to be expanded in the long term.



Figure 1:  Rainwater Tank at Chittaway Public School for Water Reuse  (Source: Wyong Shire Council)

The guidelines includes a preventative approach and emphasises risk analysis and planning issue, setting critical and operational limits and designates appropriate monitoring strategies to ensure that it functions effectively.  There are also several appendices included with case studies on recycled water schemes (both successful and otherwise) and tables to assist the environmental risk assessment process.  

As the health risks associated with recycled and reused water are always a major concern to consumers the Guidelines have applied a ‘quantitative microbial risk assessment’ (QMRA) which sets health-based targets for recycled water treatment.  The QMRA process involves four steps:

  • Hazard identification - this is the identification of the range of pathogens (infectious biological agents that cause disease or illness) which may be present in sewage or greywater and the likely concentrations and the variability in concentrations over time of the pathogens.  For each type of pathogen a representative pathogen was chosen to signify the properties of the group.  These are;
    o    For bacteria the representative is Campylobacter (the most common cause of human gastroenteritis);
    o    For protozoa it is Cryptosporidium parvum (one of several species that cause cryptosporidiosis - a parasitic disease affecting the intestines of mammals);
    o    For viruses there is not a satisfactory representative organism so an imaginary virus with the dose-response (how an organism responds to different doses of a stressor which is usually a drug or chemical) characteristics of rotavirus (which causes vomiting and diarrhea and is the most common cause of severe diarrhea in children, killing about 600,000 children every year in developing countries) and the occurrence characteristics (why, how and in what form it occurs) of adenovirus (group of viruses that infect the membranes of the respiratory tract, the eyes, the intestines, and the urinary tract) was considered.
  • Dose-response - information on the relationship between the dose of pathogens (infectious biological agents that cause disease or illness) ingested and the likelihood of developing an infection and illness.  This has been derived from human feeding studies (which are controlled feeding studies, usually in a confined setting such as a metabolic ward) and expressed mathematically with appropriate dose-response models available for the representative pathogens.
  • Exposure assessment – this estimates of the volume of water which may be ingested in passing (passively) during use of recycled water for various non-drinking purposes (e.g. toilet flushing or garden watering).  The possibility that some people would ingest larger volumes of recycled water due to accidental cross-connections with drinking water supplies was factored into the calculations and was also assessed. Deliberate misuse of recycled water (e.g. use to fill swimming pools, drinking from the tap) was not considered.
  • Risk characterisation – this is the final step in the process as it joins together the information on hazard identification, dose-response and exposure assessment to produce an estimate of the extent of the risk for each representative pathogen.  By combining this information it is then possible to calculate how much the pathogen must be reduced to produce recycled water that meets specific health-based targets.

For further information on Phase 1 see:
http://www.awa.asn.au/AM/Template.cfm?Section=Water_Recycling_Forum1 and
http://www.ephc.gov.au/ephc/water_recycling.html

Australian Guidelines for Water Recycling Phase 2

The Australian Guidelines for Water Recycling Phase Two focuses on three modules;

  • Stormwater reuse;
  • Managed aquifer recharge and;
  • Recycled water for drinking.

The draft for public consultation of the recycled water for drinking module was endorsed (by the Environment Protection and Heritage Council, the Natural Resource Management Ministerial Council and the Australian Health Protection Committee) and released in June 2007.  The draft is called ‘Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2): Augmentation of Drinking Water Supplies’ and can be downloaded from: http://www.ephc.gov.au/ephc/water_recycling.html

Australian Drinking Water Guidelines

The Australian Drinking Water Guidelines (ADWG) 2004 is the official and authoritative document on drinking water quality in Australia.  Both Phase 1 and Phase 2 discussed above integrate preventative risk management (how to prevent any risks that there may be from the recycling and reuse of water) into the water recycling guidelines.  The information on the management of recycled water quality and its use specified on Phase 1 and 2 is based on those in the ADWG 2004.  It is intended that the Australian Guidelines for Water Recycling will complement the ADWG 2004 and not supersede them.

The Australian Guidelines for Water Recycling differ from the ADWG 2004 in that they include:

  • a specific definition of safety, particularly for microbiological (unicellular or cell-cluster microscopic organisms which includes eukaryotes such as fungi and protists, and prokaryotes such as bacteria and certain algae.  Viruses, though not strictly classed as living organisms, are also included ) quality;
  • disability adjusted life years (DALYs) – this is a measure for the overall "burden of disease.” and was originally developed by the World Health Organisation, it is becoming increasingly common in the field of public health and health impact assessment.  DALYs are designed to measure the impact of premature death and disability on a population by combining them into a single, comparable measurement;
  • health-based performance targets, including the required reductions of microbial and chemical hazards – these are targets that are based solely on their affect on human health;
  • hazards of using recycled and reused water;
  • the use of reference pathogens.

The use of DALYs, performance targets and reference pathogens is based on the approach described in the World Health Organization’s (WHO’s) Guidelines for Drinking-water Quality
(WHO 2006) which can be viewed at: www.who.int/water_sanitation_health/dwq/guidelines2/en/


  
Figure 2:  The World HealthOrganisation Headquarters in Geneva, Switzerland
( Source: http://en.wikipedia.org/wiki/Image:OMS.jpg )