Perspectives on multi‐benefit water reuse systems: A confluence of water and wastewater management planning

The multiple benefits of water reuse have yet to be fully realized in our urban water management systems. One pathway to optimal implementation is to plan for their integration with wider assets in water resource or drainage and wastewater management plans. This paper explores the perspectives of water resource and wastewater management planners. Qualitative data was gathered from a workshop organized by the Chartered Institution for Water and Environmental Management (CIWEM) with 25 participants from England's Water Service Providers (WSPs), regulators (Ofwat and the Environment Agency) and consultants working within the UK water sector. The participants acknowledged that water reuse is relevant to both water resource and drainage and wastewater management planning, but that current regulatory and funding frameworks are constraining effective engagement between water resource and drainage and wastewater management planners by encouraging the development of separate plans. A general consensus of the participants was that it would be beneficial to include water reuse technology within current and future Water Resource Management Plans (WRMPs) and Drainage and Wastewater Management Plans (DWMPs). Participants suggested this could be developed through collaborative working partnerships and support from regulatory and funding frameworks that allow for the growth and development of innovative technologies and nature‐based solutions. Participants also highlighted a stronger economic case could be made for water reuse technologies if the approach seeks to capture the wider benefits and not only the ‘best value’ solution. Societal acceptance and the availability of good quality data will be key to the successful adoption of any incentivized water reuse schemes.

Agency, 2020a). With an increasing risk that water supply will exceed demand over the next 25 years, there is a need to explore approaches such as water reuse that can to reduce water demand and increase supply (Bunney et al., 2021; Committee on Climate Change, 2017; National Audit Office, 2020). Water reuse is the process of capturing and treating rainwater, stormwater or wastewater to a standard where it can be reused for other purposes such as industrial processes, agricultural irrigation and non-potable residential use (Bixio et al., 2006;Lazarova & Asano, 2013). Water reuse provides multiple environmental, economic and societal benefits (Lazarova & Asano, 2013) by conserving freshwater resources, reducing the environmental impact of treated wastewater, reducing energy costs associated with water treatment, and managing water security through the provision of a reliable water supply if adequate storage is available (Alcalde Sanz & Gawlik, 2014;Exall, Marsalek, & Schaefer, 2004;Lazarova & Asano, 2013;Voulvoulis, 2018). Water reuse schemes are increasingly being used to achieve resilience of water resources.
Wastewater has been used for irrigation purposes in China since 1957 and wastewater is predominately used for agricultural irrigation and industry in many water scarce locations such as Israel, India and countries within the Mediterranean to reduce water stress (Ait- Mouheb et al., 2020;Alcalde Sanz & Gawlik, 2014;Ricart & Rico, 2019;Voulvoulis, 2018).
Within the United Kingdom, water reuse has been considered as an option to increase resilience of future water supplies (National Infrastructure Commission, 2018;Water UK, 2016) and most frequently involves rainwater harvesting and greywater treatment systems at a building scale or for housing developments (Makin et al., 2021;Waterwise, 2020). Commercial examples include rainwater harvesting schemes such as the Honda Dealership in Manchester where 85 000 L of rainwater can potentially be captured annually for reuse. Residential schemes include Clay Farm in Cambridge that has a communal rainwater harvesting system for flushing toilets (Waterwise, 2020).
While these technologies provide an opportunity for water reuse to be explored, there is also a need to explore social factors regarding their implementation (Aitken et al., 2014). Public acceptability is a key driver in the successful implementation of water reuse schemes (Aitken et al., 2014;Beck, 2009;Nkhoma et al., 2021;Ormerod, 2016). Attitudes and perceptions of water reuse are strongly influenced by the way water reuse is communicated, 'experience and knowledge' relating to the environmental need for water reuse schemes and by engaging the public in the decision-making process (Aitken et al., 2014;Dolnicar, Hurlimann, & Grün, 2011). Public acceptability is also associated with the perceived health risks regarding the reuse of wastewater (Beck, 2009;Nkhoma et al., 2021), the original source of the water, and how the water will be used. The reuse of water for drinking has a lower acceptability than the reuse of water for irrigation or industrial use (Dolnicar, Hurlimann, & Grün, 2011).
According to Ait-Mouheb et al. (2020), water reuse should be considered in the context of a circular economy framework where water resources are reused creating a closed loop system reducing the demand for water resources and minimizing waste (Ait-Mouheb et al., 2020). This sustainable approach could also be applied to the use of stormwater and rainwater management systems as part of an integrated management strategy. However, there is a tendency for water supply and wastewater management to be considered in isolation rather than as part of a dynamic system. Traditionally, water resource management planning and drainage and wastewater management planning have been conducted in separate departments within WSPs (Water Service Providers) in England (Dobson & Mijic, 2020). This siloed approach has meant that many of the benefits of water reuse from both a water resource and drainage and wastewater planning perspective have yet to be fully realized. This is in part a reflection of the legislative requirements that have been attributed to these different aspects of water management. These can have a strong influence in the successful implementation of water reuse schemes (Frijns et al., 2016).
Within the context of England, WSPs have a statutory duty to prepare and maintain water resource management plans (WRMPs) as defined within section 37A and 37D of the Water Industry Act, 1991 (UK Government, 2022;Water Industry Act, 1999). The plans are submitted to the financial regulator, Ofwat every 5 years and detail how the water company will manage water supply and demand over a 25-year period. In 2022, WSPs in England and Wales will publish their first Drainage and Water Management Plans (DWMPs). These 'non statutory' plans will provide a framework detailing how WSPs will improve the drainage system to reduce the impact of sewer and surface water flooding and improve water quality within the environment (Water UK, 2018). However, the preparation of Drainage and Wastewater Management Plans (DWMPs) is not a statutory requirement.
Taking a systems-based approach has proven to be very effective in the development of catchment management plans for flood risk management in the UK (Collins et al., 2020;de Boer et al., 2016;Frijns et al., 2016). This collaborative approach brings multiple stakeholders and members of the public together to explore solutions for flood risk management across a catchment and has been very effective in the delivery of key environmental improvements as part of the UK Governments 25-Year Environmental Plan (Collins et al., 2020). Another example of a successful partnership approach to water resource management to achieve the targets defined within the UK Governments 25-Year Environment Plan are the development of Water Resource Regional Groups that have developed across the United Kingdom (Smith, Price, & Moncaster, 2021).
The UK Government's 25-year Environment Plan (Defra, 2018) has made a commitment to increase resilience to extreme weather events such as drought and flooding and to ensure the water sector implements long-term strategies to '… manage supply and demand' (Defra, 2018;Environment Agency, 2020b;Ofwat, 2022). However, a review conducted by the National Audit Office (National Audit Office, 2020) and the UK Parliament, Public Accounts Committee (UK Parliament, 2020) determined that not enough action had been taken by Defra, Ofwat and the Environment Agency to ensure the resilience of future water supplies. In March 2020, the Environment Agency published a National Framework for Water Resources (Environment Agency, 2020b) to address the future challenges the country will face regarding water shortages. While the framework acknowledges water reuse as a potential option to increase resilience, the report focuses heavily on the need for regional water resources planning from the perspective of water transfer schemes and reducing consumption from an average of 153 L per person per day to 110 L per person per day (Environment Agency, 2020b). A further recommendation of the national framework is for the development of regional plans by September 2023. These will be used to inform the development of future WRMPs. While there is a strong focus on WRMPs, it is uncertain as to how the recommendations from the regional plans can be used to support and inform a system based and integrated approach to water management in the United Kingdom to inform and encompass both WRMPs and DWMPs.
This study aims to explore initial perspectives related to opportunities for collaboration across water and wastewater management planning and how this can be effectively achieved. We draw on findings obtained during a workshop held with participants from UK WSPs, regulators (Ofwat and the Environment Agency) and consultants working within the UK water sector.

| METHOD
The workshop was co-designed by the research team, the Chartered

Institution for Water and Environmental Management (CIWEM) and
Water Resources South East (WRSE) to understand if there were any opportunities for collaboration across water and wastewater management teams within the UK water sector. The potential for multiple benefits of water reuse has yet to be fully realized in either water resource or drainage and wastewater management planning and by bringing together groups from each sphere the broader values can be understood and explored in future DWMP and WRMP development.
Participants were invited from CIWEM technical groups and panels to participate in the workshop. A survey was designed by the research team to capture participants' knowledge and experience throughout the workshop (Table 1), and ethics approval was obtained from the University of Exeter's ethics committee. The survey was developed offline using Google Forms and participants were given a link to the survey following the breakout group. Participants completed the survey online and individually. The core values explored in the workshop surrounded the need for diversity when developing strategic plans.
The research team focused on bringing together a diverse set of staff from across the United Kingdom that would normally work in separate departments.
There were 25 workshop participants that had been specifically targeted because of their involvement in the development of DWMPs and WRMPs within their organization. The workshop was delivered online using Zoom and divided into four stages ( Figure 1). The first stage comprised two presentations to provide the context of the workshop within the current regulatory framework and to provide guidance regarding future collaborative working partnerships, approaches to uncertainty, best value assessment and to define a collaborative approach to funding and delivery. Participants were assigned to one of two breakout rooms depending on whether they worked within the water resource or drainage and wastewater management planning. This information had been obtained prior to the workshop when participants confirmed they would like to participate in the workshop. Participants were not made aware of any selection criteria. Each group was presented with a series of questions to stimulate discussion and debate regarding the main challenges they faced in the development of their DWMPs or WRMPs. Notes were taken by the research team throughout each discussion. At the end of the breakout session, each participant was asked to complete a series of both open and closed questions (Q1-Q8, Table 1).
During the third stage, participants from each group were brought together for a summary of their individual discussions, after which they were informed that they had been separated on the basis of whether they worked within the water or wastewater part of the business. There was then a short presentation to deliver some additional information and participants were then randomly assigned to two different breakout sessions within the online platform Zoom. For this part of the workshop participants were not pre-assigned to a breakout room. This was to ensure that each group contained a mix of participants from both water resource and drainage and wastewater management planning. During this session the groups were presented with a series of questions to explore opportunities and challenges for collaboration during the development of DWMPs and WRMPs and the role of water reuse. Notes were taken by the research team throughout the discussion. The notes were validated at the end of each breakout session during the group discussion where the person taking the notes presented the breakout group findings to the wider group for discussion and to ensure the information captured was an accurate account of the breakout room discussions. At the end of the session, participants were requested to complete a series of questions.
Following the breakout session all the participants were brought together to share the outcomes of each discussion and agree recommendations for future WRMPs and DWMPs. Finally, participants were asked to complete a series of Likert style questions to explore their perceptions of the relevance of water reuse within either the DWMPs or the WRMPs as well as their views on the outcomes of the workshop. All of the notes were collated, and a thematic analysis was conducted to identify the main themes from each breakout group discussion. The survey sample data was too small and selective to undertake inferential statistical analysis and a descriptive analysis was conducted based on participants' responses.

| RESULTS AND DISCUSSION
Participants were asked if their job role was more aligned to WRMPs or DWMPs. Of the 25 participants, 10 were aligned with DWMPs and 15 were aligned with WRMPs. For WRMP participants 20% worked at a strategic level within water management planning with 20% working in research and development, 13% in planning and 7% working in an engagement role. For the DWMP participants, 20% worked at a strategic level in water management planning with 20% working in research and development, programme, and delivery management T A B L E 1 Questions participants were asked to complete following each breakout session.

Question
Response type Option

| Key challenges and opportunities identified for DWMPs
Understanding the wider role that customers can play in both stormwater and demand management was identified as a key challenge for the DWMP participants ( The development of DWMPs is intended to be a highly collaborative process involving all the Risk Management Authorities (RMAs).
However, the general feeling within the breakout group discussion was that the non-statutory nature of the DWMPs was making it difficult to develop an integrated and multi-organizational approach to water management (Table 3, D4).
This led on to further discussion within the breakout group where participants highlighted the difficulties of assessing the cost benefit of 'non-traditional' solutions within the current regulatory framework. It was suggested that this could be overcome if there were a more consistent approach to assess long term benefits and solutions (Table 3, D5).
Many participants within the breakout group expressed concern regarding expectations and maturity of DWMPs in comparison to WRMPs, the ability to conduct network modelling across hundreds of catchments and how the DWMPs will integrate with other plans and priorities for the future (Table 3, D6). The ability to achieve deadlines within the designated timescales was also reflected within the questionnaire response (

| Water reuse and the technologies available to achieve this
To reinforce the discussion within each breakout session the participants were asked to complete a series of questions. These were designed to explore participants' knowledge and understanding of water reuse and water reuse technologies in the context of the plan for which they were most aligned. This section explores how the questionnaire response supported many of the discussions within the breakout session regarding water reuse.
T A B L E 3 Quotes taken from the DWMP workshop exploring challenges and opportunities (D = DWMP Participant). While this technology can be used to purify water and is an effective approach for the desalination of seawater and brackish water it can also be used following secondary treatment within wastewater treatment plants (Tota-Maharaj & Hills, 2020). However, it is uncertain as to why this was not considered by the DWMP participants.
A negative public perception regarding wastewater reuse and regulatory constraints is creating additional restrictions on the application of wastewater reuse. Participants reflected on how customer perception is influenced by the way in which these schemes are introduced and the language that is used. It was suggested that terms such as 'effluent reuse' or 'wastewater reuse' invoke negative emotions associated with the use of dirty water. This has also been supported within the academic research (Wester et al., 2016). Public acceptability is a key challenge in the successful implementation of water reuse schemes and is influenced by many factors such as the way in which water reuse is communicated, how the water will be used, the perceived health risks associated with the end use and trust in the WSP motivations (Aitken et al., 2014;Ormerod, 2016;Voulvoulis, 2018).
However, public acceptability for water reuse is also influenced by 'experience and knowledge' relating to the environmental need for water reuse schemes and engaging the public in the decision-making process (Aitken et al., 2014;Dolnicar, Hurlimann, & Grün, 2011).
While this was not discussed within the breakout groups it highlights an opportunity for WSPs to work together in collaboration with stakeholders and community groups in target locations to explore water reuse as an option to increase resilience of water resources.
Participants expressed concern regarding water quality regulations, the ownership, installation and maintenance of rainwater harvesting schemes and the detrimental impact on health and customer perceptions if these are not managed correctly ( One participant in the breakout group, highlighted the difficulties evaluating wastewater reuse schemes against supply side schemes such as water metering and whether the benefits of these schemes can be compared effectively. This led to a discussion regarding whether the economic, environmental, and societal benefits of water reuse schemes were being adequately quantified across all activities within a catchment. Participants highlighted the difficulties achieving this within the framework of the current water planning guidance and how a systems-based approach to quantify the benefits of a water reuse scheme at a catchment scale would enable the identification of synergies within the wider system of water management (Table 4, R5).
Participants were asked within the questionnaire if they were able to name the manager within their organization that was responsible for leading the opposing plan. This was to gain an understanding of the level of awareness between WRMP and DWMP participants of F I G U R E 2 Participant response to Question 5 'should water reuse form part of the plan you are most aligned to?' including the types of water reuse technologies those that selected 'yes' considered to be relevant to this plan.
the person responsible for leading the opposing plan. For the WRMP participants, 73% can name the manager within their organization who is responsible for leading the DWMP plans. 7% are not able to name the manager. 13% do not consider the question to be applicable and 7% did not respond (Figure 4). When asked how closely they interact with the manager responsible for leading the DWMP plan (Table 1, Question 7), 47% work 'closely' with the DWMP manager.
20% work 'infrequently' with the DWMP manager but acknowledge there is a link. 7% do not currently interact with the DWMP manager.
13% do not consider the question to be applicable and 13% did not respond.
60% of DWMP participants were able to name the manager responsible for leading the WRMP plan. 20% did not consider the question to be applicable and 20% did not respond. When asked how closely they interact with the manager responsible for leading the WRMP plan, 60% of DWMP participants stated they 'closely' interacted with the WRMP manager. This was either through daily contact because they worked in the same team or through attendance at weekly and monthly meetings. 10% stated they worked 'occasionally' with the WRMP manager, 20% considered the question to be 'not applicable' and 10% did not provide a response. These results would suggest that both WRMP and DWMP teams are aware of the manager responsible for leading the opposing plan with the majority of participants agreeing that they closely interact with this person.

| Key challenges and opportunities identified by DWMPs and WRMPs within the collaborative breakout session
There was further discussion regarding water reuse in the combined breakout rooms (Table 1, Stage 3). It was generally considered that water reuse is relevant to both water resource and drainage and wastewater planning and is a necessary tool for adapting to the future pressures of an increasing population, urbanization, extreme weather events and climate change. In the questionnaire participants were asked to identify links that join water management plans to water reuse and the benefits and opportunities that water reuse systems create for their organization. Both WRMP and DWMP participants identified a reduction in water demand, an increase in water efficiency, effective stormwater management and energy reduction as key links joining water management plans to water reuse.
Within the questionnaire, participants were asked what opportunities water reuse systems create for their organization (Figure 3). The responses were categorized into four main themes including capacity management, increased flood resilience, stakeholder engagement and resource efficiencies. For WRMP participants water reuse provided an opportunity for demand reduction with wastewater considered a 'lost resource' that could be used for capacity management. For DWMP participants water reuse was considered an opportunity to 'claw back' headroom and the reuse of both greywater and rainwater at source would reduce the need for water abstraction, water treatment and transfer providing greater water supply resilience. It was also generally considered that the reuse of greywater and rainwater at source would contribute to effective stormwater management and increase flood resilience by reducing the amount of water flowing into the drainage system.
The effective and more efficient use of available resources through better integration across flood risk and water resource management allows for a more sustainable and resilient approach to water management by reducing the impact of surface water flooding and reducing the need for water abstraction. This would also provide new opportunities to model the integration of water reuse data into existing plans and explore decentralized options. This highlights the need for greater collaborative working partnerships between external stakeholders, regulators, RMAs, customers and between WRMP and DWMP teams this is supported within a regulatory and funding framework.
Not all the solutions proposed by participants in the breakout session and the questionnaire were aimed towards WSP operations.
Other opportunities included 'Putting a value to water' by changing customer mindset and accountability through incentivized water reuse schemes. This was highlighted as a potential opportunity by the DWMP participants in the questionnaire response. Within the breakout session customer perceptions regarding the value of water were considered a key influence in the use of rainwater harvesting as a primary source of water within the household. This was supported with evidence of good practice in countries where water scarcity was an issue and where the use of decentralized systems had become the norm. However, the cost of retrofitting these systems often T A B L E 4 Quotes taken from the questionnaire in response to Questions 4, 6, 7 and 8 (Table 1) and workshop breakout session 1 (Figure 1). R = questionnaire response.

R1 Cost Benefit
'It might be different in different companies … accessing clean water is usually cheaper than wastewater reuse.'

R2 Water Quality
'Who owns that and who manages that? Does the water company have to make sure the water quality is not impacted from a potable or toilet flushing point of view?'

R3
Planning 'It has to be through a consistent and agreed best value planning process that takes account of the costs, limitations of technology, the regulations, the positive and negative environmental benefits and the carbon footprint associated with that type of option compared with others.'

R4
Engagement 'A fundamental change is required with lots of interdisciplinary and inter party engagement … it needs that level of engagement from different parties … throughout the whole process for these marginal schemes to be more mainstream and linking them to SuDs is really important.'

R5 Consistency
'We need to better align the approaches so they are consistently taking account of those synergies between a water reuse scheme and how it could provide benefit to both sets of plans.' outweighed the perceived benefit. The cost of water was considered a barrier to public acceptance because it was cheap compared to other utilities and the public considered reused water to be dirty and of poor quality. Incentivized water reuse schemes were proposed as a potential mechanism to encourage customers to 'value water'. Participants discussed how water reuse schemes could be adopted at any scale as long as there was societal acceptance and it could be demonstrated that the schemes were cost effective, fulfilled regulatory requirements and changing environmental and climate pressures.
However, it was also acknowledged that this requires effective communication of water reuse to engage and encourage public acceptance of water reuse technologies. For this to be effective, information also needs to be provided explaining the environmental need, the source of the water, how the water will be used and how it will be treated to alleviate concerns regarding health risks (Aitken et al., 2014;Beck, 2009;Bell & Aitken, 2008;Nkhoma et al., 2021;Ormerod, 2016

| CONCLUSIONS
This study aimed to bring together groups from water resource and drainage and wastewater management planning to explore the F I G U R E 4 Participant response to Questions 14 to 18. multiple benefits of collaborative planning for future DWMP and WRMP development. However, the key findings are based on the views of a limited number of people and while they provide insight, they may not be more broadly representative and similar workshops may uncover different/convergent/divergent issues.
Within the context of this research, the key findings were as follows: • Water reuse is a beneficial tool for water resource and drainage and wastewater planning and would be supported through increased collaborative working partnerships between external stakeholders, regulators, RMAs, customers and between WRMP and DWMP teams.
• Current regulatory and funding frameworks are constraining effective collaborative stakeholder and customer engagement.
• These frameworks are also a barrier to the adoption of innovative technologies, such as reverse osmosis, advanced oxidation, or greywater reuse, particularly as potable water is cheaper to supply than wastewater reuse is to implement.
• Incentivized water reuse schemes could encourage customers to 'value water'. However, these schemes will need to demonstrate they are cost effective, fulfil regulatory requirements, and meet the needs of changing environmental and climate pressures.
• Options assessments often seek to achieve 'best value' and may not capture the wider benefits of water reuse schemes. A stronger economic case could be made for water reuse technologies if a catchment-based approach is adopted during planning and optioneering.
• The availability of good quality data is a constraint in the development of long-term water resource and water management planning solutions