Summary of Australia's Water Reuse Guideline or Regulation for Rainwater Collected Onsite for Onsite Non-potable Water Reuse
This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Rainwater Collected Onsite.
On this page:
- Technical basis
- Onsite non-potable water reuse applications approved for use in Australia
- Water reuse treatment category/type
- Additional context and definitions
- Onsite non-potable reuse specifications (table)
- Upcoming regulations
- References
- Disclaimer
This page is a summary of the country’s water reuse law or policy and is provided for informational purposes only. Please always refer to the country for the most accurate and updated information.
In Australia, onsite non-potable water reuse The use of treated onsite collected waters for non-potable purposes at the single-building or district scale. This reuse application excludes the use of recycled water from a centralized treatment and distribution system for landscape irrigation or commercial uses. applications include garden watering, car washing, toilet flushing, among others. The source of water rainwater collected onsite Precipitation collected at the district or regional scale is classified separately under 'stormwater.' is specified by Australia as rainwater. The write-up adapted Australia’s terms when discussing sources or uses of water to match the Regulations and End-Use Specifications Explorer's (REUSExplorer's) terms.
Technical basis
Australia has developed guidelines to support the use of onsite collected rainwater for onsite non-potable reuse applications, including for garden watering, irrigation, toilet flushing, vehicle washing, clothes washing and fire protection (NWQMS, 2006; 2009). Similar to the World Health Organization (WHO) water reuse guidance, Australia uses health-based microbial log-reduction targets (LRT) and chemical concentration targets for water quality monitoring (NWQMS, 2006; NWQMS, 2022; WHO, 2017). These LRT and chemical concentration targets vary based on the source of water and its different end uses, allowing the risk assessment of microbial and chemical hazards that could be present in wastewater to determine benchmark risks. Australian guidelines use disability adjusted life years (DALYs) for microbial hazards only, converting the estimated probabilities of infection or illness into burden of disease (NWQMS, 2006). DALYs are used to weigh health impacts in terms of severity and duration of disease and the number of people affected. One DALY is equivalent to the loss of one year of full health and it is the sum of years of life lost due to premature mortality (YLLs) and years lived with a disability (YLD) associated to a specific disease or health condition prevalence (WHO, 2023). In drinking water, DALYs are primarily used for microbial hazards, with 10-6 DALYs per person per year (pppy) being approximately equivalent to 1 case of diarrheal disease per 1,000 people per year. Australia set a benchmark risk threshold of 10-6 DALYs per person per year (pppy) for onsite non-potable water reuse. This risk threshold applies to microbial log-reduction targets (LRTs) only, and chemical concentration targets follow the Australian drinking water guidelines (ADWG, 2022).
Treatment guidelines are summarized in the table by source and end use. The technical basis for developing specifications and/or removal of debris, microbial contaminants and other relevant indicators is specified within Australia’s guidance documents for water recycling (NWQMS, 2006; 2008; 2009). The guidelines are intended to be used as an authoritative reference for states and territories in Australia to provide the scientific basis for implementing regulations.
Onsite non-potable water reuse applications approved for use in Australia
The National Water Quality Management Strategy (NWQMS) (2009) defines the following specific onsite non-potable water reuse applications for onsite collected rainwater from rooftops of residential dwellings, where the roof-water is stored in a covered tank:
- Garden watering
- Irrigation
- Toilet flushing
- Vehicle washing
- Fire fighting
- Clothes washing
Additional onsite non-potable reuse applications for rainwater are listed on Table A6.1 (NWQMS, 2009).
Water reuse treatment category/type
Australia states that recycled water that meets the defined health-based microbial LRT and chemical concentration targets specified by the national, state or territory authority is considered safe for the specified end use.
Treatment guidelines are provided for onsite non-potable water reuse in Australia. NWQMS (2006; 2008) outlines specific treatment processes that are known in water treatment engineering:
- Primary: The physical treatment process to remove suspended solids, organic nitrogen, phosphorus, heavy metals, some parasites and some particulate-associated microorganisms.
- Secondary: The removal of dissolved and suspended organic material through sedimentation, biological treatment and/or chemical treatment. This level of treatment reduces microbial pathogens, biodegradable organics, volatile organic compounds and nutrients.
- Tertiary: The removal of suspended solids, biological oxygen demand and pathogenic organisms. Different levels of tertiary treatment include dual-media filtration with coagulation, membrane filtration, reverse osmosis, chlorination, ozonation, activated carbon, advanced oxidation, disinfection and ultraviolet light. These reduce microbial pathogens and chemical hazards.
Additional context and definitions
NWQMS (2006) and NWQMS (2008; 2009) comprise the first and second phase of the Australian Guidelines for Water Recycling, respectively. The water quality targets, including chemical concentrations and microbial treatment performance (e.g., LRTs of pathogens in source waters), are the key health-based targets for onsite non-potable water reuse. The guidelines are intended to be used as an authoritative reference for states and territories in Australia to provide the scientific basis for implementing regulation.
NWQMS (2006; 2008; 2009) provides guidance on preventative measures for recycled water systems for onsite non-potable water reuse. Appropriate storage methods for rainwater include lagoons, constructed or natural wetlands, subsurface wetlands, managed aquifer recharge and storage tanks. Australia encourages the collection and recycling of water for onsite non-potable reuse, but underscores to defer to state and territories for regulations which include:
- Contact of regulatory authority to determine specific requirements for recycled water harvesting schemes
- Adoption of recycled water plumbing codes (e.g., color coding)
- Buffer zones, tree and shrub screens, fencing
- Management controls
- Prohibition of recycled water use in specific areas
- Identification of appropriate treatment processes
- Identification of on-site controls (e.g., buffer zones, control of access, method, time and rate of application)
Onsite non-potable water reuse specifications
The specifications presented in the table include some parameters to be monitored in non-potable recycled rainwater in Australia. The microbial LRTs on the table were derived from first principles through Quantitative Microbial Risk Assessment (QMRA) techniques using microbial indicator data from rainwater collected from rooftops in combination with pathogen to indicator ratios derived from sewage (NWQMS, 2009). The LRTs calculation assumes different levels of exposure depending on the application, and pathogen doses equivalent to 10-6 DALY, i.e., 3.8×10-2Campylobacter (NWQMS, 2006; 2008). The NWQMS federal guidelines provide detailed information about these parameters (NWQMS, 2006; 2008; 2009).
Summary of Australia's Onsite Non-potable Water Reuse Specifications
| Recycled Water Class/Category | Source Water Type | Water Quality Parameter | Specificationsa | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)b |
|---|---|---|---|---|
|
Onsite non-potable water reuse |
Rainwater collected onsite |
Copperc |
<100 mg/kg of soil after irrigation |
Not specified |
|
Zincc |
<200 mg/kg of soil after irrigation |
|||
|
Campylobacter jejuni |
No LRT for irrigation, dust suppression, food crops, garden watering or firefightingd |
Source = NWQMS (2006; 2009)
a Australia uses guideline chemical concentrations published in the Australian drinking water guidelines (NWQMS, 2022).
b Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the state-specific regulations.
c Monitored for its impact on soils, not for public health reasons (South Australia Health, personal communication, November 28, 2023).
d Treatment is not required if exposure prevention practices are followed (NWQMS, 2009).
Upcoming regulations
No upcoming reuse regulations related to onsite non-potable water reuse were found for Australia.
References:
Geneva: World Health Organization (WHO). 2017. Potable reuse: Guidance for Producing Safe Drinking-Water.
Geneva: WHO. 2023. Disability-adjusted life years (DALYs).
National Water Quality Management Strategy (NWQMS). 2022. Australian Drinking Water Guidelines (ADWG) 6 (version 3.8).
NWQMS. 2009. Australian Guidelines for Water Recycling: Managing Heath and Environmental Risks (Phase 2). Stormwater Harvesting and Reuse.
NWQMS. 2008. Australian Guidelines for Water Recycling: Managing Heath and Environmental Risks (Phase 2). Augmentation of Drinking Water Supplies.
NWQMS. 2006. Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1).
Please contact us at waterreuse@epa.gov if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.