Water reuse in the U.S.: a comprehensive look at progress, challenges, and future prospects

Historically, the initial applications of recycled water were largely for agricultural irrigation and groundwater replenishment. Over the past decades, the scope has broadened significantly. Eva Steinle-Darling provides historical context, explaining that early forms of water reuse, like "sewage farms," were primarily for disposal purposes. "Untreated wastewater was applied to agricultural fields because they didn't know where else to put it," she explains. Over time, these practices evolved into more intentional and regulated uses, such as groundwater replenishment and non-potable reuse in industrial settings​​.

On the industrial side, water reuse has seen significant growth, driven by sustainability goals and water scarcity challenges. Steinle-Darling elaborates, "Most of the industrial reuse, which is exploding as a practice, is really focused on facility internal recycling efforts. In an effort as part of our industrial partners' sustainability goals to lessen their water footprint, they take less water in from the outside and send less water out of their facility"​​. This shift is particularly notable in sectors like semiconductor manufacturing and beverage processing, where the implementation of advanced purification technologies allows for repeated reuse within the facility.

Peter Grevatt also emphasizes the expansion of water reuse in industrial applications. "There are increasingly recycled water uses within the industrial space, driven by the need to address water stress and ensure sustainable water supply for growing populations," he notes​​. This trend reflects a broader shift towards sustainable water management practices across various sectors.

Drivers of water reuse

The drivers behind the increased adoption of water reuse practices are multifaceted. While water scarcity remains a primary motivator, other factors such as environmental sustainability, regulatory requirements, and corporate sustainability goals also play significant roles.

The drivers behind the increased adoption of water reuse practices are multifaceted, thought water scarcity remains a primary motivator

Glickstein points out that water scarcity has historically been a key driver: "The birth of water recycling was in some of these very dry, arid communities where we were just looking for another water source"​​. However, he also highlights emerging drivers such as stormwater management and wastewater management, particularly in urban areas with aging infrastructure. "In New York City, the main driver for on-site water reuse systems in new buildings is not scarcity of water, but stormwater and wastewater management," he explains​​. Insofar as new buildings can be more self-sufficient in treating and reusing the water internally, it can reduce the load on ageing infrastructure that's in the ground. It is an interesting new application of on-site water reuse.

Grevatt emphasizes the role of population growth in water-stressed areas: "Many of the communities that have experienced the greatest water stress are also areas where the population is rapidly growing. This population growth in water-stressed areas is leading to an increase in the safe practices for water recycling"​​. He also mentions unique cases like the Hampton Roads Sanitation District, which uses water recycling to combat land subsidence in addition to providing a reliable water source​​.

Steinle-Darling notes the shift from supply-side concerns to environmental protection as a driver: "We’re seeing reuse projects that are driven by discharging avoidance, trying to avoid the discharge of nutrients to sensitive water bodies. If I'm going to have to treat this water to such an extent, why would I put it in the ocean instead of reusing it for beneficial purposes?"

Another driver outside of scarcity is water quality. “As our understanding of new contaminants in water increases, some of the same suite of technologies that were established for water recycling become very appealing”, says Glickstein. Many of the advanced treatment technologies used in water recycling can be used to remove PFAS, so communities that weren't looking to these technologies to recycle water are now considering them. “Once communities are cleaning their effluent with technologies like reverse osmosis or granular activated carbon, they might start exploring beneficial uses for that incredibly pure water,” he adds.

Policy and regulatory changes

Recent policy and regulatory changes have been pivotal in supporting water reuse and advancing circular economy principles. These changes, primarily at the state level, have provided the necessary framework for the expansion of water reuse practices, particularly direct potable reuse (DPR). Both Glickstein and Grevatt highlight the significance of state-level regulations in advancing DPR. Glickstein points out that states like Colorado and California have pioneered regulations facilitating DPR, a move that encourages other states to follow suit. "We're seeing almost one state per year in the last few years grappling with the process to approve projects for direct potable reuse," he says​​.

Grevatt elaborates on the regulatory developments in California, noting the state's comprehensive approach to setting guidelines and conducting extensive research to ensure safety and efficacy. "California's regulations are extraordinarily stringent. Not everyone will necessarily pick up what California has done, but it has contributed significantly to an understanding of what the key questions are that have to be answered, what goals need to be achieved. I think it will at least lay the groundwork for others to say, alright, we can build on what California has done and decide what's right for our state,” he observes.

"Population growth in communities in water-stressed areas is leading to an increase in the safe practices for water recycling", Peter Grevatt (WRF)

Steinle-Darling adds that the repeal of prohibitions and the establishment of supportive policies are critical steps in enabling DPR projects. "We’ve seen a transition from the past 15 years or so when the National Research Council (NRC) considered the DPR solution of last resort. Now, at least a half dozen states have explicit rules or policies supporting the development of DPR projects"​​. She notes that states like Arizona and Florida are also developing their regulations, driven by the demand from utilities and communities.

Technology readiness and contaminants of concern

The technological readiness of water recycling systems is well-established, with mature technologies capable of achieving the required water quality standards. Steinle-Darling asserts: "The technologies are there. I do not doubt in our capability to produce any particular water quality that we need to achieve"​​. These technologies include advanced treatment processes like reverse osmosis and granular activated carbon, which are essential for removing contaminants and ensuring the safety of recycled water.

"While the technological readiness of water recycling systems is well-established, the challenge is making them cost-efficient and operable", Eva Steinle-Darling (Carollo Engineers)

Steinle-Darling emphasizes that the challenge now is making these technologies cost-efficient and practically operable. "We're not the International Space Station; we're not a semiconductor manufacturing facility that requires ultra-pure water. There are different levels of treatment goals we need to achieve for certain levels of use, and drinking water is certainly a very high-level standard, but it is not the highest that we have for water"​​. This perspective highlights that the existing technologies are more than capable of meeting the stringent standards required for potable reuse.

Grevatt supports this view, noting that the technologies are proven and reliable when properly operated and maintained. "We are confident that the technology is ready for water reuse operations, but it has to be operated properly and maintained in a very careful way by the utilities"​​. He points out that The Water Research Foundation has a portfolio of over 250 research projects focusing on water reuse, which underscores the extensive research and development efforts supporting these technologies.

Concerns about contaminants, including PFAS, are central to discussions about water reuse. Both Glickstein and Steinle-Darling emphasize that advanced treatment technologies used in water recycling are effective in removing these contaminants. Glickstein reassures that "many of these technologies that are employed for advanced purification of recycled water are very similar to the ones being recommended for the removal and destruction of PFAS"​​.

Steinle-Darling adds that the potable reuse sector is particularly well-equipped to handle PFAS, having monitored and treated for a broad range of emerging contaminants for over two decades. "Potable reuse is essentially ahead of the game as far as PFAS is concerned relative to the rest of the industry," she states​​.

Grevatt also highlights the effectiveness of these technologies in addressing emerging contaminants like PFAS. "The treatment train for water reuse operations, such as the one used by the Orange County Water District, is very effective in removing PFAS and other contaminants"​​. This capability positions water reuse systems ahead of many traditional drinking water treatment facilities in terms of dealing with new and emerging contaminants.

The economic viability of technologies

Implementing water reuse technologies involves substantial initial investments in advanced treatment systems, infrastructure, and operational capabilities. However, these costs must be weighed against the long-term benefits and cost savings that water reuse can provide.

Glickstein highlights the favorable comparison of water reuse projects to other new sources of water. "When you compare these various water reuse projects against other new sources of water in a water scarcity situation, reuse often compares really favourably from an economic viability perspective," he explains​​. Traditional options such as building new dams, developing reservoirs, or desalination tend to be more expensive and less sustainable in the long term.

"In a water scarcity situation, reuse projects compare favourably against other new sources from an economic viability perspective", Ben Glickstein (WateReuse Association)

Steinle-Darling emphasizes the importance of making water reuse technologies cost-efficient and practically operable. "The real key is to make it cost-efficient and practically operable. We have various alternative approaches, but the projects are site-specific depending on your incoming water quality and regulatory requirements"​​. This perspective underscores the need for tailored solutions that meet specific local conditions and regulatory frameworks.

Grevatt supports this view, noting that the economic viability of water reuse is enhanced when considering the broader economic and environmental benefits. Grevatt highlighted the example of Hampton Roads: “[Water reuse] is also helping to reduce the land subsidence that has been occurring over time in coastal Virginia. The combination of land subsidence and sea level rise is a very big problem for coastal areas, so here is another example where the utility is not only providing a reliable source of water for communities over time, but they are also helping to reduce the issue of land subsidence. These additional benefits contribute to the overall economic case for water reuse.

To make water reuse projects more economically viable, especially for smaller communities, increased funding and financial support are essential. Glickstein stresses the importance of government funding in overcoming the economic barriers to water reuse. "A lot of our focus at the WaterReuse Association is on advocating for more government funding to make these projects financially viable"​​. Government grants, loans, and subsidies can significantly reduce the financial burden on communities looking to implement water reuse technologies.

Resource recovery from wastewater treatment

The potential for resource recovery from wastewater treatment plants is an exciting frontier in the realm of water reuse. Energy recovery from wastewater is one of the most promising aspects of resource recovery, providing significant environmental and economic benefits. Grevatt highlights several successful examples of energy recovery from wastewater treatment processes. "The Milwaukee Metropolitan Sewage District and DC Water have extensive operations in place to recover energy from wastewater treatment"​​. These facilities use anaerobic digestion to produce biogas, which can be used to generate electricity and heat, thus reducing the overall energy footprint of the treatment process.

Anaerobic digestion is a key technology in this area, as it breaks down organic matter in the absence of oxygen, producing biogas — a mixture of methane and carbon dioxide. This biogas can be captured and used as a renewable energy source. "There are already lots of opportunities in this area, and I believe we will see growing potential for future expansion," Grevatt adds​​.

Steinle-Darling emphasizes the importance of adopting these technologies more widely. " I think the real challenge for recovering the embedded energy in wastewater is the pace of adoption in our industry," she notes​​. The infrastructure in many wastewater treatment plants is ageing, and integrating new technologies requires significant investment and planning. However, the benefits of energy recovery make it a worthwhile endeavour for many utilities.

In addition to energy, wastewater treatment plants can also recover valuable nutrients, such as nitrogen and phosphorus, which are essential for agricultural use. Nutrient recovery not only helps to close the nutrient loop but also reduces the environmental impact of wastewater discharge.

Grevatt points out the extensive operations in place for nutrient recovery at facilities like the Milwaukee Metropolitan Sewage District and DC Water. "These organizations are already recovering valuable resources like nutrients through their wastewater treatment processes," he explains​​. Nutrients recovered from wastewater can be processed into fertilizers, which can then be used in agriculture, reducing the need for synthetic fertilizers.

Steinle-Darling highlights the technological readiness of nutrient recovery processes. "There are many interesting technologies out there for nutrient recovery," she says​​. Technologies such as struvite precipitation, which recovers phosphorus in a form that can be used as a slow-release fertilizer, are becoming more common in advanced wastewater treatment facilities.

The integration of energy and nutrient recovery into wastewater treatment plants exemplifies the principles of the circular economy, where waste streams are transformed into valuable resources. Glickstein underscores the importance of this holistic approach. "Many of our members and communities that are creating a water recycling project of any sort are becoming next-generation full reclamation facilities, where water reuse is part of a bigger story that involves energy generation and the reuse of biosolids for agriculture"​​.

This comprehensive approach not only maximizes resource efficiency but also enhances the economic viability of water reuse projects. By recovering energy and nutrients, wastewater treatment plants can offset some of their operational costs and generate additional revenue streams.

Despite the clear benefits, integrating resource recovery technologies into existing wastewater treatment infrastructure presents challenges. Steinle-Darling points out that one of the main hurdles is the age of current infrastructure. "We are still treating wastewater with technology from 20 years before I was born, so it’s really difficult to implement these newer technologies on a large scale"​​. Upgrading facilities to incorporate advanced resource recovery systems requires significant investment and long-term planning.

Public trust and acceptance

Building public trust and acceptance is a critical component of successful water reuse projects. Glickstein and Grevatt stress the importance of early and consistent community engagement. Glickstein advises starting public communication well before project implementation to build a foundation of understanding and support. "We've found that consistency, transparency, and clarity are all important and that public support will improve when the need is understood," he asserts​​.

Glickstein emphasizes that public acceptance varies significantly across communities. "The degree to which a community understands the need for these projects or what goes into one of these projects really varies city by city"​​. In many communities that are now building potable reuse projects, community engagement started decades ago. “You start with concentric circles of trust building and identify strong community advocates that can understand the treatment technology and the benefits,” he explains.

There is a generational shift towards acceptance of circular economy principles, driven by education and awareness of environmental issues

Grevatt shares similar sentiments, highlighting the importance of community engagement in preventing misunderstandings and opposition. "Bringing school kids to facilities like the Orange County Water District helps build future workforce and public understanding," he notes​​. These educational efforts are essential for fostering long-term support and acceptance of water reuse practices. Glickstein concurs, since projects often take 20 years from conception to construction, “the school children who you're speaking to are maybe the people who are voting on the bond for the construction project”.

Steinle-Darling emphasizes the need for clear communication and the use of accessible language to convey the benefits and safety of water reuse projects. "Engineers often use incredibly inaccessible language, which can be interpreted as scary. You need to have a strong initial message about why the project is necessary," she explains​​. This approach is crucial for addressing potential public concerns and building a foundation of trust and acceptance. She points to the generational shift towards greater acceptance of circular economy principles, driven by education and increasing awareness of environmental issues​​.

Future outlook: opportunities and challenges

The landscape of water reuse in the United States is poised for significant changes over the next decade. As the country grapples with increasing water scarcity, climate change, and the need for sustainable water management, advancements in technology, policy developments, and shifts in public attitudes will play crucial roles.

Glickstein anticipates that technological advancements and regulatory support will continue to drive the expansion of water reuse practices. "Technological advancements are going to continue to improve the viability of water recycling projects, which will hopefully allow access to more and more communities," he predicts​​. He expects an acceleration in water reuse because of regulatory support. Also, industrial sector reuse will increase, driven not just by water scarcity, but by public perceptions and by the environmental goals of many industrial water users.

Steinle-Darling foresees further integration of advanced treatment technologies and innovations. She emphasizes the importance of shifting public and industry mindsets to fully embrace potable reuse as a viable water management strategy. "What we really need to be talking about is this change in public awareness, acceptance, policy, and the mindset of our water industry leaders to say: 'This is something I can stand behind,'" she asserts​​.

Regulatory frameworks will continue to evolve as water reuse is recognised as a critical component of sustainable water management

Grevatt highlights the potential impact of digitalisation and AI in optimizing water treatment processes. As utilities adopt these tools, they will be better equipped to manage complex water reuse systems and respond to emerging challenges. He also underscores the need for ongoing public engagement and education to address emerging contaminants and other challenges. "The biggest challenges will have to do with public communication and engagement," he says​​.

Regulatory frameworks will continue to evolve, reflecting the growing recognition of water reuse as a critical component of sustainable water management. State-level regulations, federal guidelines, and international collaborations will shape the future of water reuse. Building and maintaining public trust is an ongoing challenge. Continuous efforts in education, transparent communication, and community engagement are necessary to address concerns and foster acceptance.

Conclusion

The evolution of water reuse in the United States reflects a dynamic interplay of technological innovation, regulatory advancements, and public acceptance. As water scarcity and quality issues become more pressing, the role of water reuse will continue to expand, supported by robust policy frameworks and community engagement. The insights from experts like Ben Glickstein, Eva Steinle-Darling, and Peter Grevatt underscore the importance of a comprehensive approach to water management, integrating advanced technologies, regulatory support, and proactive communication to ensure sustainable and resilient water systems for the future. With continued advancements and growing acceptance, water reuse is set to play a crucial role in addressing the water challenges of the 21st century.