Recycled water management
To supply or use recycled water from a wastewater treatment plant, water industry entities are required to obtain approval from Department for Health and Wellbeing (DHW). Additionally, connected third parties who use recycled water supplied from a wastewater treatment plant (WWTP) must attain a DHW recycled water use approval.
Recycled water approvals contain regulatory conditions which inform the approval holder of their responsibilities under the Wastewater Regulations 2013.
Recent recycled supply approvals contain conditions relating to:
- operational monitoring and control
- instrumentation
- verification and validation
- operation and maintenance
- supporting programs including procedures, management plans, training, and auditing
- reporting requirements for incidents or emergencies, non-compliance, and annual reports.
Assessing recycled water systems
To attain a recycled water supply approval, DHW assess the suitability of the recycled water produced from a WWTP for the intended application based on the:
- level of treatment and control at the WWTP, and
- amount of on-site preventative measures in place at the recycled water irrigation site which reduces the public exposure to the recycled water.
Log Reduction Values (LRV) are applied to both wastewater treatment barriers and to the onsite preventative measures to ensure there is sufficient pathogen reduction in place to safely use the recycled water.
Log reduction value targets for recycled water end uses
The Australian Guidelines for Water Recycling (Phase 1) (PDF 2.1MB) sets targets for the reduction of microbiological hazards found in sewage, that are based on a level of ‘tolerable risk’ to the public, and the predicted exposure volumes arising from different types of recycled water use. The targets are expressed as log reduction values (LRVs) and are dependent on the type of end use.
| Recycled water use category | Virus LRV | Protozoa LRV | Bacteria LRV |
|---|---|---|---|
| Dual reticulation - indoor AND outdoor use e.g., toilet flushing, washing machines & garden use |
6.5 | 5.0 | 5.0 |
| Dual reticulation - indoor OR outdoor use only e.g., toilet flushing & washing machines, or outdoor garden use. |
6.0 | 4.5 | 5.0 |
| Municipal irrigation e.g., ovals, parks, golf courses and dust suppression |
5.0 | 3.5 | 4.0 |
| Commercial food crops e.g., fruit and nut trees, vineyards, cereal crops |
6.0 | 5.0 | 5.0 |
| Landscape irrigation e.g., trees, shrubs, public gardens |
5.0 | 3.5 | 4.0 |
| Non-food crop e.g., trees, turf, woodlots, flowers |
5.0 | 3.5 | 4.0 |
Applying LRVs to recycled water systems
To meet the target LRVs for a specific recycled water end use, LRVs can be applied to:
- wastewater treatment barriers and
- on-site preventative measures (also called exposure reduction controls) which prevent the public from being exposed to the recycled water
Wastewater treatment barriers
Wastewater treatment barriers can be tested or ‘validated’ to determine the level of pathogen reduction that can be achieved during a range of conditions including peak flow. Validation must involve comprehensive monitoring in real time to provide assurance that the water quality objectives are continuously met. Following validation, the 5th percentile LRV demonstrated during validation can be applied to the barrier.
In the absence of a validation, there are a range of conservative default LRVs that can be applied to wastewater treatment barriers if the required control and monitoring is in place (Table 2). For some treatment barriers, such as membrane bioreactors, chlorine disinfection and UV disinfection, there are nationally agreed validation protocols (WaterVal - WaterRA) which define the criteria for assigning LRV.
Refer to the LRV table template (XLSM 291KB) for information on the expected verification, monitoring and control required when applying default LRVs to wastewater treatment barriers. Note, there is no default LRV values for filtration (UF, MF, media etc) or reverse osmosis. Instead, a barrier specific validation is required to claim LRV for these treatment technologies.
| Wastewater treatment barrier | Virus LRV | Protozoa LRV | Bacteria LRV |
|---|---|---|---|
| Secondary treatment via an activated sludge process | 0.5 | 0.5 | 1.0 |
| > 50 days lagoon detention (following primary treatment) | 1.0 | 1.0 | 1.0 |
| > 25 days lagoon detention (following secondary treatment) | 0.5 | 0.5 | 0.5 |
| Chlorine disinfection with a free Cl contact time (Ct)* | 1.0 - 4.0 | 0.0 | 1.0 - 4.0 |
| UV Disinfection - pre-validated system | 0.5 - 4.0 | 0.5 - 4.0 | 0.5 - 4.0 |
| Membrane Bioreactor (MBr)# | 1.5 | 2.0 | 4.0 |
* Refer to Table 1 of the Chlorine Disinfection Validation Protocol, WaterVal 2017 for applicable LRV.
#
Alignment with Tier 1 operating envelope in Table 1 MBr Validation Protocol. Water Val 2017.
In South Australia, there are a number of advanced WWTPs that achieve all the LRV requirements for unrestricted irrigation. All other WWTPs supplying recycled water require on-site preventative measures to be applied by the user to safely irrigate.
On-site preventative measures
When using recycled water, it may be necessary to implement on-site preventative measures to prevent public exposure.
The amount of restriction required is dependent on the quality of the recycled water being used and the type of use proposed. Lower quality water (recycled water with a lower LRV) requires additional end use restrictions to adequately reduce the public exposure to the recycled water. In contrast, recycled water that is approved to be irrigated without restrictions, indicates that the sewage has been treated to a high quality, achieving the entire LRV requirement for the end uses.
On-site preventative measures can be applied to protect people in the vicinity of the irrigation area, or to protect consumers of irrigated produce. Examples of on-site preventative measures where LRV can be applied
Examples of on-site preventative measures where LRV can be applied.
To protect the public in the vicinity of the irrigation area:
- night-time irrigation
- no public access to the irrigation site
- >25m buffer distances
- spray drift control
- drip or subsurface irrigation.
To protect consumers from produce irrigated with recycled water:
- drip irrigation of a raised crop
- crops with no ground contact and skins removed
- crops with no ground contact and heavily processed
- crops cooked or processed before consumption
- withholding time between harvest and sale.
Calculating the total LRV for a recycled system
When assessing if the treated effluent supplied from a WWTP is suitable for a particular end use, the total LRV applied to the wastewater treatment barriers, and the LRV applied to on-site preventative measures must meet or exceed the minimum LRV targets identified for the end use (table 1).
Wastewater treatment barrier LRV + Onsite Preventive Measure LRV = Total LRV requirement for the end use.
Risk management plans
A risk management plan (RMP) (also called a recycled water management plan) documents the risk-based approach for managing the treatment of wastewater, and the production, supply, and safe use of recycled water. The content and structure of the RMP should follow the framework of the Australian Guidelines for Water Recycling.
The Department for Health and Wellbeing has developed RMP templates which may be used:
- Supply RMP: Required when a WIE supplies recycled water from a WWTP to one or more third-parties.
- Supply and Use RMP: Required when a Water Industry Entity (WIE) supplies recycled water from a WWTP and uses recycled water for irrigation on their own land.
- Use RMP: Required by an irrigator using recycled water supplied from a WWTP.
RMP templates
- Supply RMP template (DOCX 450KB)
- Supply and Use RMP template (DOCX 461KB)
- Use RMP template (DOCX 188KB)
Contact
For further information on recycled water management contact:
Wastewater Management team
Health Protection and Regulation
Department for Health and Wellbeing
Email: healthwastewatermanagement@sa.gov.au
Phone: (08) 8226 7100.