Purified recycled water - helping to build thriving water resilient communities
At a glance
Urban water supply is at a crisis point. In the face of climate change and rapidly growing populations, it is our professional responsibility as changemakers to re-think our traditional relationship with water – particularly wastewater. By taking an interdisciplinary and diversified approach to our water planning and assessment, we believe there is collective industry power to unlock opportunities and accelerate our shared vision of securing reliable, high-quality drinking water supplies for people and planet.
At GHD, we understand that meaningful conversations are needed to overcome the challenges and that all voices need to be heard on this people-first journey.
Two major sources of water that offer sustainable climate-resistant solutions to our water crisis are our oceans (for cities near the coast) and recycled wastewater. In Australia, we already see seawater desalination in operation across major urban areas. Since 2000, widespread acceptance has been achieved for using recycled wastewater across non-potable applications, such as irrigation and dual pipe. However, from a potable supply standpoint, wastewater reuse and broad community acceptance remain limited. Herein lies the opportunity; to treat wastewater to a high standard for use in drinking via potable reuse or purified recycled water (PRW).
This article is the first in a series of perspectives from our Wastewater and Water Treatment Specialists on the topic of purified recycled water as a viable drinking water supply option. These have been produced with an acute understanding of the nuances that influence decision making and an appreciation that, in many cases, more than one solution is required if we are to deliver positive water outcomes that both respect nature and help communities manage supply and demand.
Benefits of choosing purified recycled water (PRW)
Utilising wastewater as a resource is a significant step towards creating communities that are resilient, inspired, productive and connected. Compared to alternative water supply options, such as seawater desalination, PRW is likely to present several advantages, including greater energy and operational efficiencies. Proven safe for drinking, PRW is currently in use in over 35 cities across the world.
On average, 70% of the water supplied to our cities becomes wastewater. This is where GHD sees significant opportunities – to directly link the use of drinking water with a new source to augment the same drinking water supply.
The benefits of augmenting our drinking water by way of PRW include:
- Sustainability and resilience: Water systems that are rainfall independent, with available water volumes directly linked back to a community’s usage.
- Economic benefits: PRW is generally a more cost-efficient solution when compared to other water supply augmentations such as seawater desalination.
- Reduced carbon footprint: In comparison to other water supply options, PRW is a sustainable and energy-efficient option
- Improve wastewater management: Reduced volumes of wastewater released into our environment.
How to create and use PRW
At its highest level, purified recycled water is the process of treating wastewater to a level that makes it safe and suitable to go back into the drinking water supply at some point. For any given project, the embryotic stage is always an investigation into available schemes assessed against their suitability (based on the specific needs of a community). PRW schemes can be arranged so that the reuse is direct – via raw or treated water augmentation, or indirectly – via an intermediate environmental buffer as either groundwater or surface water augmentation.
Direct and indirect PRW schemes offer different advantages. The type of scheme best suited to a particular region depends on the various attributes of its existing water supply system. In general, the preference is usually for indirect use with the inclusion of an environmental buffer that assists in two keyways: addressing certain key risks and gaining community acceptance. Direct potable reuse is not yet commonplace and requires additional treatment barriers and careful and rigorous risk and quality management. In our following perspective, ‘Direct potable reuse – a sustainable, safe and cost-efficient water supply solution’, we discuss the benefits of direct schemes versus indirect schemes in greater detail.
The key features of direct versus indirect PRW schemes are outlined below:
- Direct schemes involve sending the (highly treated) water directly into the supply network.
- Indirect (surface water) schemes involve sending the water to a reservoir to blend with other sources and be further treated prior to supply.
- Indirect (groundwater) schemes involve pumping the water into an aquifer for later extraction and treatment prior to supply.
The IPR and DPR process
Unlocking opportunities and managing challenges
From a technical standpoint, the challenges regarding using PRW are widely understood and have been successfully overcome in schemes around the world. Critical to success is ensuring a comprehensive review of the location, existing water supply system, wastewater management, and any other locally unique factors that may impact the suitability of PRW.
The most apparent challenges PRW projects face are achieving community acceptance (due almost entirely to the “yuk factor” perception of drinking recycled water) and securing regulatory approval. Community understanding and support are pivotal to the overall success of PRW projects. We believe these can be achieved by putting people first in the approach and prioritising community education and engagement to build social licence.
Health departments must be convinced that risks will be adequately managed and that sufficient monitoring and redundancy are in place to prevent contamination and protect public health. From a sustainability standpoint, environmental regulators will want to see that projects are cognisant of environmental impacts related to wastewater management and discharges, waste generation and energy usage.
While reusing significant volumes of wastewater is regarded as a sustainable approach, environmental considerations require further addressing. These and other key considerations will be discussed further as part of additional perspectives from our Wastewater and Water Treatment Specialists on the topic of purified recycled water.
Up next: Direct potable reuse – a sustainable, safe and cost-efficient water supply solution.
To learn more about how GHD can assist you in considering and developing PRW for your system, please reach out to our Wastewater and Water Treatment specialists in your region: