Integrating Spatial Concerns into Water Reuse Regulations: Insights from the European Union and the Iberian Peninsula

Abstract

Water scarcity in Southern Europe, driven by climate conditions and water-intensive land use, is promoting water reuse adoption. Water reuse regulations are emerging, but little is known about integrating spatial concerns into their contents. This study examines how spatial issues are addressed within water reuse regulations adopted by the European Union (EU), Portugal, and Spain. Through a comparative content analysis, this research explores the inclusion and distribution of key terms related to water drivers, spatial concepts, and land use types within key sections, preamble, objectives, permitting, risk assessment, monitoring, and governance. The findings show that Portugal and Spain exhibit poorer integration of water scarcity compared to the EU, and Portugal does not address it in its objectives. In contrast, broad spatial terms are more prominent in Portugal, while Spain emphasises conservation and environmental areas more. Spatial terms are distributed differently across sections, reflecting different regulatory approaches. Surprisingly, none of the regulations link to plans. They mention risk management plans and, occasionally, circular economy and river basin management plans. Agriculture and urban activities dominate, although Portugal emphasises industry and green areas. This study highlights the need for more spatially informed water reuse regulations.

1. Introduction

Increasing water scarcity events in various locations, alongside changes in population and climate, have intensified the need for coordinated efforts between land use planning and water resource management [1]. Water scarcity is often understood as an imbalance between supply and demand, but it can also be a matter of access [2]. Even when water is physically available, some regions or communities may experience scarcity due to governance failures, unequal distribution, or inadequate infrastructure [2]. Moreover, certain land use types or practices can also exacerbate water scarcity [3]. Water scarcity is therefore a constraint interrelated with spatial planning and the implementation of climate adaptation actions [4]. Integrating land use, water, and other relevant policies (e.g., energy and agriculture) is necessary to adopt a more holistic approach to managing water resources. Land use planning helps prevent water scarcity and fosters adequate locations for water reuse initiatives [5]. Land use planning may support the development of wastewater reuse infrastructure and initiatives, which can help meet growing water demand in a sustainable manner [4]. In addition, it can facilitate early and broad engagement with the public, key stakeholders, and organisations in the planning process for water reuse initiatives [6]. Despite the role of land use planning in preventing water scarcity, it often operates in isolation from water management, leading to missed opportunities for integrated solutions [1].

Water management considerations should be integrated with land use strategies in water reuse policies and regulations, which must ensure not only the sustainable supply of water but also equitable access to it across different territories. This approach helps to avoid the “take, make, waste” model and design new infrastructure with water efficiency and reuse in mind [5]. However, questions remain about what must be integrated and how this should occur [7]. Integration can be understood in various ways, such as governance integration, which involves bringing stakeholders together at different levels and incorporating local knowledge [8]. It can also refer to the alignment of policies and procedures. In the specific context of this study, integration focuses on embedding water resources and water initiatives as core principles within land use plans and strategies [9]. Relevant to water scarcity and reuse, this integration can be understood as the need to coordinate and align different aspects of water management, land use planning, and environmental protection to address water scarcity and promote sustainable water reuse [10]. Within this scope, two primary approaches have emerged: a technical approach, which emphasises innovations for water reuse, recycling, and reduced consumption, and a governance approach, which focuses on institutional and organisational dimensions, including policy and regulations [5], as well as spatial and water-related considerations. Governance is a complex concept, particularly in the context of sustainability, encompassing a wide range of definitions, frameworks, and approaches [11,12]. Although it has been the focus of extensive scholarly debate, a detailed exploration falls beyond the scope of this article. Governance approaches for water reuse involve, among other aspects, an integrated water resources lens; adapted institutional arrangements and decision-making processes; social, economic and territorial power relations balances; stakeholder participation mechanisms; co-creation processes; and adaptive strategies [13,14,15,16].

Water reuse regulations need to consider land use and territorial features and be tailored to specific local contexts [4,17]. Water reuse poses risks that necessitate effective monitoring and control. This involves evaluating the total volume of water available, including its quantity, quality, and intended purpose, to ensure appropriate treatment and means for transport or distribution. Additionally, potential impacts on soil, human health, and other environmental factors must be considered in relation to local land use pressures and territorial features [5]. Moreover, water reuse must be managed through a robust risk management plan that identifies relevant actors and their responsibilities. This plan should consider land use and territorial features, recognising, for example, that water reuse for agricultural irrigation may not be suitable in all areas [18].

This article aims to understand how water scarcity and territorial concerns are incorporated into water reuse regulations in the European Union (EU) and the two Iberian countries, Portugal (PT) and Spain (ESP), where climate-related pressures on water availability have increasingly intensified. In the scope of this study, the broad concept of “land use planning” is often used as an umbrella term to encompass land use, spatial, location, and territorial concerns. This research addresses the following questions: Are spatial concerns integrated into water reuse regulations? If yes, how do the patterns of this integration compare between different jurisdictions? For this purpose, the article develops a content analysis to examine how water scarcity and spatial concerns are embedded in the referred water reuse regulations. It analyses the EU (Regulation (EU) 2020/741 of the European Parliament and of the Council), Portuguese (Decree-Law No. 119/2019), and Spanish (Royal Decree 1085/2024) regulations. Although studies on regulations and policies are frequent in the literature, this study offers a novel approach by analysing regulations and categorising specific features of their content through a systematic content analysis approach, providing straightforward and comparable insights about real-world regulatory frameworks.

This article is structured into five sections. The second section outlines brief insights identified in the literature on the research topic. The third section presents the research design, materials, and analytical approaches. The fourth section presents the findings derived from the analysis. The fifth section presents the discussion where the findings are discussed, considering the methodology, data, literature, and practical implications. The conclusions summarise the main contributions and potential directions for future research.

2. Insights from the Literature

The scientific literature conceptualises the term “integration” regarding several critical concerns. First, integration is conceptualised as the need for strong articulation between land use planning and water resources planning systems [9,19,20]. This approach may integrate water scarcity and reuse into planning instruments and consider approval processes for treatment systems [19]. This integration is critical to maintaining and restoring surface water quality, implementing sustainable management measures, protecting ecosystem services, and reinforcing adaptation strategies to climate change. The integration could be achieved by establishing measures and rules in integrated plans that prevent land use impacts on water quality and quantity, creating synergies between water protection and land use control [20]. In addition, integration refers to the institutional arrangement integrating planning and regulatory approaches across multiple agencies and levels of government [9,21,22]. Faragher and Carden, 2023 [21], argue that the complexity of water systems spans various levels of government and involves coordination within different departments and directorates. Furthermore, diverse stakeholder perspectives and knowledge are crucial in decision-making, particularly in land use planning and water governance [23,24].

This section provides key insights from the scientific literature about the integration between water scarcity, territorial concerns, and water reuse. It aims to clarify the emerging concerns raised by the scientific community and to support the analysis of how water reuse regulations address these concerns, which are developed further in this article. It is based on a set of sixty-three scientific articles or reviews published in journals in English in the last five years, identified in the Scopus platform using the keywords “water scarcity” and “land use planning” or “spatial planning”, and “water reuse” and “land use planning” or “spatial planning” in the fields of environmental and social sciences, selected in November 2024.

The analysis of the identified articles crossing water scarcity and land use planning or spatial planning reveals that climate change is emerging as a common and critical challenge [25,26]. The interconnectedness between water scarcity and land use is recognised [19,21] but still poorly explored by specific studies. In contexts of water scarcity, land use is often closely tied to water management, watersheds, water allocation, and relevant legislation. In contrast, land use planning is most often associated with broad development control and climate change [9,20]. The timeline of publications indicates that, although land use is not a new topic in the context of water scarcity and reuse, land use planning has only recently gained attention.

The analysis of the location of publications shows that while the United States and China lead in the number of publications, European countries such as the Netherlands, Spain, and Germany appear to have stronger collaborative links with other nations. In the European context, contributions are prominent in Germany, the United Kingdom, Austria, Romania, Spain, and the Netherlands. Interestingly, the Netherlands, Spain, and Portugal publications act as bridges, linking Europe to countries on other continents, such as South Africa, Australia, and China. Additionally, publications from the United States show a strong research collaboration with European countries, facilitating connections between Canada and Europe. Despite China’s significant contributions as a leading publisher in the field, its collaboration with other countries remains relatively limited.

A further analysis of key research themes revealed four distinct groups of authors, each focusing on interconnected topics within water resources, land use, and climate change. One group centred their research on the Soil and Water Assessment Tool (SWAT), hydrological modelling, and climate change (e.g., [27,28]). Another group focused on water resource management and climate adaptation, particularly in China (e.g., [29,30,31]). A third group examined broader environmental impacts, including life cycle analysis, water footprints, and ecosystem sustainability [32,33]. Lastly, another group of authors focused on land and water use in drylands, including remote sensing, irrigation practices, and vegetation management in Central Asia (e.g., [34,35,36])

Land use planning offers diverse contributions to addressing water scarcity and fostering water reuse initiatives. One contribution referred to in the literature relates to the alignment of goals between water management and land use planning policy instruments and the creation of synergies between them, especially in locations with high water consumptive uses, complex water conflicts, or constraining water-related territorial features such as areas prone to scarcity [9,19,37]. Sustainable land use practices, such as reforestation and agroforestry, permeable urban land uses and runoff reduction, groundwater recharges, and restraining water uses to water availability, are among the suggestions found in the literature (see, for example, [25,26,38,39]). These measures may also facilitate adaptation to natural disasters like floods and soil erosion, particularly in wetter climates [40]. Land use planning strategies play a critical role in curbing excessive water use and supporting water reuse in high-density development settings [1,41] or facilitating the adoption of water reuse technologies by creating infrastructures for rainwater harvesting or distributing treated water for reuse [42]. Nevertheless, the need for a basin-level, holistic approach to balance socio-economic demands with ecological sustainability is stressed as a relevant criterion to consider when integrating water reuse technologies and approaches into land use plans [21,43]. According to the literature, specific interventions, such as limiting agricultural land conversion and preserving forests, are crucial for maintaining water flow and quality, as noted by Pouya and Turkoglu, 2020 [44], and Carse, 2012 [45]. Promoting drought-resistant crops and sustainable irrigation practices is also mentioned as relevant to support water reuse while reducing overall demand [46,47]. Adopting land use controls around reservoirs and implementing zoning regulations to prevent adverse impacts on water quality and availability are also referred to as valuable steps [20]. Together, these diverse strategies highlight the multifaceted role of land use planning in ensuring sustainable water resource management and reuse.

Water reuse regulations should account for the critical influence of location and land use on water production and availability and recognise the need to engage a broad range of stakeholders, including both land and water users, beyond solely private water rights holders [48]. The literature identifies three main concerns regarding the integration of water reuse regulations with land use planning. The first relates to the need for a holistic approach integrating water reuse planning and land use concerns [19,20,44]. Water reuse regulations and water resource management plans must be integrated with land use planning and zoning regulations to ensure that land use activities within water basins are compatible with and support the protection of water resources [37]. In addition, the distribution infrastructure on land must be integrated into planning strategies and instruments [19]. Second, the regulations must ensure institutional coordination across sectors and vertically at different levels [19,41]. Third, water reuse regulations must adopt more flexible regulations, increasing monitoring, control, and assessment. Accordingly, land use activities should be rigorously controlled, with their environmental impacts systematically assessed, potentially through permitting procedures [20,23,49].

From the brief insights drawn from the literature presented in the previous paragraphs, although the importance of integrating water management with land use planning and water-related territorial features is, in general, recognised, little is known about the specificities of water reuse regulations and how they should incorporate spatial concerns, especially in scarcity contexts. This article seeks to enrich this subject within the scientific community by adding new insights.

More specifically, from a regulatory standpoint, water reuse frameworks may attend to regional hydrological, climatic, ecological, and infrastructural variability, ensuring enforceability, equity, and sustainability. In areas identified as water-scarce or drought-prone, regulations attend to minimum levels of water reuse and establish enforceable financial or operational requirements, with reuse thresholds proportionate to the severity of local water stress. Regulatory approaches may consider reuse zones based on geographic and climatic parameters, including precipitation regimes, elevation, and coastal proximity, thereby ensuring spatial precision in regulatory applicability. They may also differentiate requirements according to land use categories and related environmental features, like specifying standards for greywater reuse in urban contexts, treated wastewater in agricultural applications, and industrial process water recovery in manufacturing zones. At the river basin scale, reuse regulations should align with integrated water reuse management principles, ensuring legal coherence across jurisdictions, protection of downstream rights, and basin-wide sustainability. In ecologically sensitive areas, regulations may consider constraints or require adaptive measures to prevent degradation, incorporating provisions for nature-based solutions such as constructed wetlands, where appropriate. Finally, regulatory frameworks should be tiered according to governance capacity and infrastructure availability, establishing enforceable minimum standards while allowing for flexible compliance pathways suited to local conditions and ensuring the due involvement of the various water users and stakeholders in the decision-making processes.

The following section presents the methodology adopted to explore further how water reuse regulations integrate these concerns.

3. Materials and Methods

3.1. Introduction to the Documents for Analysis

The emergence of water reuse in Europe has been driven by advancements in treatment technologies, escalating water scarcity, and the need for cost-effective solutions for non-potable applications [5,18]. The European Environment Agency has highlighted that water scarcity affects a significant portion of EU land and population annually, underscoring the urgency of implementing such measures [50]. The Water Reuse Regulation adopted by the European Union in 2020, establishing minimum standards for reclaimed water quality to ensure safety and public confidence, may contribute to addressing these challenges in member states. Before this, Portugal, facing increasing water scarcity, proactively adopted water reuse regulations in 2019, setting a precedent for other member states. Spain followed in 2024 with its regulations, reflecting a regional commitment to sustainable water management. Both countries, especially their southern regions, increasingly integrate water reuse and desalination strategies to adapt to climate change and secure water resources for current and future needs [4,6].

The EU Regulation 2020/741 establishes minimum standards for reclaimed water used in agricultural irrigation, addressing water scarcity caused by urbanisation, agriculture, and climate change. It promotes treated wastewater reuse as a safe, cost-efficient alternative to conventional water sources while harmonising standards across member states to encourage adoption. The regulation supports the circular economy by encouraging nutrient recovery, reducing dependency on synthetic fertilisers, and enhancing sustainability. Key provisions include mandatory risk management plans to ensure water safety and monitoring requirements for consistent water quality. The regulation also requires permitting water reuse projects, ensuring transparency, traceability, and public confidence. Unifying standards and promoting innovative practices enhance water security while protecting the environment and public health. In addition, it is also worth mentioning two more recent related documents which complement the EU water reuse regulatory landscape: the 2022 Commission Guidelines (2022/C 298/01), which focus on compliance and transparency, and the 2024 Delegated Regulation (EU) 2024/1765, which supplements EU Regulation 2020/741 by providing technical specifications for risk management. Their emphasis, however, is mainly on technical management and stakeholder coordination, providing no specific guidance on spatial concerns. This explains solely focusing on the 2020 regulations.

The Portuguese Water Reuse Regulations are established under the Decree-Law No. 119/2019. These regulations address water scarcity in Portugal, which is driven by increased consumption, urbanisation, and climate change. It promotes the reuse of treated wastewater for non-potable purposes such as irrigation, landscaping, and industrial use, offering a cost-effective and environmentally sustainable alternative to conventional water sources. By integrating water reuse into national strategies, the law supports circular economy principles, reduces greenhouse gas emissions, and enhances resilience to climate change. The law establishes a framework for safe water reuse, requiring risk-based evaluations to ensure compliance with health and environmental standards. It sets out licensing procedures for producing and using reclaimed water and outlines strict monitoring requirements to maintain water quality. These measures aim to protect public health, safeguard natural ecosystems, and reduce pressure on traditional water supplies. The Spanish Water Reuse Regulations are established under Royal Decree 1085/2024, reinforcing Spain’s commitment to sustainable water management in response to increasing water scarcity, particularly in the southern regions. These regulations promote the reuse of treated wastewater for non-potable applications such as agricultural irrigation, landscape irrigation, industrial processes, and urban uses, aligning with circular economy principles. By integrating water reuse into national policies, the decree reduces dependence on freshwater resources, lowers water treatment costs, and enhances climate resilience. It establishes a risk-based framework to ensure the safe use of reclaimed water, setting quality standards, monitoring protocols, and licensing requirements for its production and application. These measures aim to protect public health, safeguard ecosystems, and support sustainable economic activities, aligning with European Union regulations on water reuse and ensuring harmonised and controlled implementation across Spain.

3.2. Analytical Steps

To address the research questions outlined in Section 1, an analytical approach based on a content analysis, a method widely tested in similar studies within environmental policy [20,51,52], is used to examine the three water reuse regulations. It assumes that the stronger the embeddedness of spatial concerns, the stronger their capacity to adopt water reuse regulations in a spatial manner. The analytical steps consisted of (i) conducting a preliminary reading of the three documents to identify relevant terms related to water scarcity and spatial concerns; (ii) developing a coding table with the selected terms for analysis and their rationale (see

Table 1. Coding table with the list of terms searched in the regulations.

Themes	Keywords	Query Words	Rational
Water Driver	Scarcity	water scarcity, drought	While drought refers to a temporary natural event caused by reduced rainfall, scarcity represents a long-term imbalance where water demand exceeds sustainable supply. Scarcity often reflects structural pressures from overuse or pollution, while drought highlights short-term climatic extremes. Identifying these terms helps assess whether regulations adopt a proactive, strategic framing or a reactive, emergency-based approach to water management. Their use signals how urgently and structurally water reuse is positioned within national or EU-level legal frameworks.
Spatial Terms	Land/Territory	territory, territorial, spatial, land, soil	These terms are relevant because they reflect how regulations consider the physical and territorial context of water reuse practices. For instance, zoning refers to spatial regulations that determine permissible land uses and their compatibility with water reuse logistics. For instance, restricting reuse infrastructure near sensitive land uses (e.g., residential zones or nature reserves) is a zoning-based concern. Infrastructure refers to the physical systems required for transporting, storing, and distributing treated wastewater, which must be spatially integrated within land use and planning instruments. References to river basins and territory indicate an ecological or hydrological approach, while terms like local and land show sensitivity to land use and planning boundaries. The inclusion of transport or transfer is especially relevant, as treated wastewater often needs to be conveyed across jurisdictions or land uses, raising logistical, environmental, and governance considerations. These keywords highlight the extent to which regulations incorporate spatially explicit spatial planning and infrastructure provisions.
	Local	place, local, location, space
	Area	area, zone
	Transport	transfer, transport, transportation
	River basin	river, river basin, hydrographic basin
	Plan	plan, planning
Activities and land use types	Agriculture	agriculture, agricultural	These terms are used to identify sectors where water reuse is applied or encouraged. Their frequency helps map regulatory priorities and potential mismatches between legal intentions and real-world practices. For instance, strong mentions of agriculture or urban indicate alignment with water-intensive land uses, while terms like wetland, ecosystem, forest, or green area point to stricter environmental concerns. Understanding which land uses are emphasised reveals how comprehensive the regulatory vision is in promoting water reuse across different territorial functions.
	Urban	urban, public space
	Industry	industry, industrial
	Green areas	wetland, ecosystem, landscape, green area, garden
	Forest	forest, forestry

); (iii) counting the frequency of each term’s occurrence across the entire document to gain an overall perspective of embeddedness of the spatial and land use concerns; and iv) counting the frequency of each term within main sections of the document, such as the preamble; scope and objectives; permitting, compliance and enforcement; risk assessment; monitoring and quality standards; and governance and public engagement (as detailed in

Table 2. Regulations’ major sections and their relevance for the analysis.

Sections	Relevance to Spatial and Activities Keywords
Preamble	Acknowledges the importance of the concept. Spatial words, if they appear, may set the context for addressing resource constraints through spatial planning [19,20].
Scope and Objectives	Defines overarching concerns and provides a high-level acknowledgment of land use planning in reuse strategies [19], including the objectives, scopes, and obligations.
Permitting, Compliance, and Enforcement	Defines procedures for obtaining official permission to operate (licensing) and how parties ensure they follow the rules and the ability to effectively control land use activities essential for water reuse. Spatial terms may reflect how land use planning supports compliance (e.g., site selection for reuse facilities) [23,49].
Risk Assessment	Acknowledges the risk associated with water reuse and its mitigation, and highlights potential risks in water reuse systems that may be tied to land use concerns and the threats posed by land use changes to water resources recharge, especially in drought-prone zones [21].
Monitoring and Quality Standards	Covers monitoring mechanisms, and quality and quantity indicators to ensure safe water reuse. The inclusion of spatial terms may indicate the land use requirements for reuse, highlighting how different land contexts may affect the implementation of water reuse systems [20].
Governance and Public Engagement	Covers the cooperation, delegation, institutions, and public information. Spatial terms like local or territorial could highlight how governance structures support land use planning for water reuse, and their crucial role in institutional arrangements that integrate planning and regulatory approaches across multiple agencies and levels of government [9,21].

), to display how the terms are incorporated in each regulatory frameworks. To reduce language differences, the English versions of the documents were analysed. Terms were searched both in the text and the tables of the documents. To ensure reliability and avoid biases, the coding table was first applied independently by each author, and then, the results were discussed and merged. The agreement measurement between the three authors, using Fleiss’s kappa [53], was 0.82, which is considered almost perfect. Since the documents vary in length, word frequency was normalised using the formulas below to ensure a fair comparison. For this purpose, the following equations were used:

$$The frequency of land use planning related word={\displaystyle \frac{\begin{array}{c}Number of times a specific word is mentioned \\ in a document\end{array}}{Total number of words in a document}}\ast 100$$

$$The frequency of land use planning related word={\displaystyle \frac{\begin{array}{c}Number of times a specific word is mentioned \\ in a part of the document\end{array}}{Total number of words in the document}}\ast 100$$

The following section presents the results of the analysis, derived from the application of the methodological framework outlined earlier.

4. Findings

4.1. Overall Embeddedness of the Spatial and Land Use Concerns in the Regulations

The analysis of the frequency of the terms referred to in the three documents (European Union (EU), Portugal (PT), and Spain (ESP)), as represented in Figure 1, reveals that their patterns differ slightly.

The EU regulations use the terms “scarcity” and “drought”. However, “scarcity” is predominant. “Water availability” is also present, though less frequently than the previous terms. Though present, spatial terms like “area”, “local”, “space”, and “territory” are not frequently used. The use of “plan” is mainly related to risk management plans, with only a single mention tied to the EU action plan for the circular economy and the river basin management plan. The references regarding land use types indicate that “agriculture” and “urban” are the most frequently referenced types of land uses and activities, followed by “industry” and marginally by “forest”. Terms such as wetlands, coastal zones, or green are also absent from the EU regulation, despite their relevance to ecosystem-based reuse strategies and environmental planning.

Compared with the EU, the Portuguese regulation refers to “scarcity” or “drought” much less frequently, though “drought” is slightly more referred to than “scarcity”. References to “water availability” are minimal and appear even less frequently than in the EU regulation. Spatial terms, like “area” and “land”, are only marginally more referred to than in the EU regulations. However, terms like “local” or “territory” have higher occurrences. Although “plan” is mentioned in the Portuguese regulation, it is scarcely referred to in comparison to the other documents. Unlike the EU Regulations, where references to “plan” are mainly related to management plans, in Portugal, they are related to landscape and river basin management plans. For land use-associated terms, despite following the pattern of the EU regulations, showing a stronger embeddedness of terms regarding “agriculture” and “urban”, though on a smaller scale, it shows a stronger emphasis on “industry” and “green areas”.

The Spanish regulations follow the pattern of the EU regulations, giving more substantial use of the term “scarcity” than “drought”. Moreover, “water availability” is mentioned more frequently than in the EU and even surpasses the use of “scarcity” and “drought” within the same regulation. On the contrary, the use of terms related to areas or zones is poorer. It refers to the “river basin” in the context of water reuse, with a stronger emphasis than the EU regulations. The use of the word “plan” is the most frequent in comparison with the other two documents. It is mainly related to risk management plans. Regarding land use-associated terms, the Spanish regulation differs from the EU regulation by including many more references to “forest”, followed by “agriculture”, “urban”, and “industry”. “Green areas”, though enriched with terms like “wetland”, are less referred to in these regulations.

When comparing the Portuguese and Spanish regulations, the Portuguese place slightly more emphasis on “drought”, while the Spanish regulation places more emphasis on “scarcity”. For spatial terms, the Portuguese regulation more frequently uses terms like “local” and “territory”, while the Spanish regulation highlights “river basin” and “wetland”. In terms of activities and land uses, the former gives more weight to “urban” and “industry” while the latter, on the other hand, places more emphasis on “forest”. The most notable difference is the use of “plan”, the most frequently used word in the Spanish regulation, mainly referring to risk management plans. In contrast, the Portuguese regulation uses “plan” far less, and when it appears, it is associated with landscape planning and river basin management plans.

Table 3. Examples of sentences of the regulations using the analysed terms present in the documents.

Scopes	Extracted Sentences Using Terms Under Analysis
Water Drivers	“The water resources of the Union are increasingly coming under pressure, leading to water scarcity and a deterioration in water quality. In particular, climate change, unpredictable weather patterns, and drought are contributing significantly to the strain on the availability of freshwater, arising from urban development and agriculture.” (EU, Preamble) “The frequency and intensity of droughts and their environmental and economic damage have increased dramatically over the past 30 years. Thus, situations of high needs, combined with low or even absence of rainfall and high evapotranspiration, may cause situations of imbalance and scarcity in the availability of water.” (PT, Preamble) “Ultimately, water reuse is currently seen as an essential element within integrated water management that allows it to contribute to the fulfilment of both the protection objectives of the public hydric domain, and the environmental objectives (…); confront water scarcity and drought; promote the circular economy; and support adaptation to climate change.” (ESP Preamble)
Spatial Terms	“Hazard means a biological, chemical, physical or radiological agent that has the potential to cause harm to people, animals, crops or plants, other terrestrial biota, aquatic biota, soils or the environment in general.” (EU, Article 3) “For the purposes of this Regulation, it should be possible for treatment operations and urban wastewater reclamation operations to take place in the same physical location, using the same facility, or different, separate facilities.” (EU, Preamble) “Sprinkler irrigation at distances greater than 70 m from residential areas or spaces for public use.” (PT, Annex II, Table 1) “In the places of production and use of water for reuse, information and signage must be placed, in the terms defined by decree of the member of the Government responsible for the area of the environment.” (PT, Article 28) “These plans will recognize the obligation of, at least, the progressive replacement of the use of water for human consumption for the bucket of streets, in watertight and ornamental flows or the river of large urban green areas, for the use of regenerated water or other supply sources, all depending on the requirements that are detailed for each territorial scope in hydrological planning.” (ESP, Article 26-3) “The use of regenerated waters for the artificial recharge of water bodies, as well as to satisfy the water needs of wetlands and other aquatic ecosystems will be considered, for the purposes of this Regulation, not as uses but as environmental destinations, and its process will be carried out in accordance with that established in the RDPH, being subject to the quality requirements specified in annexes I and II of this regulation.” (ESP Article 3-3)
Activities and land use types	“Water reuse could contribute to the recovery of the nutrients contained in treated urban wastewater, and the use of reclaimed water for irrigation purposes in agriculture or forestry could be a way of restoring nutrients, such as nitrogen, phosphorus and potassium, to natural biogeochemical cycles.” (EU, Preamble) “Water quality standards for reuse for irrigation to protect agricultural, forestry, and soil crops.” (PT, Annex I, A) “Likewise, as a means to promote the circular economy and reinforce adaptation to climate change, it is necessary to regulate the use of regenerated water for certain uses, encouraging reuse within the urban water cycle itself.” (ESP, Preamble)

presents a few examples of sentences in the documents using the terms.

4.2. Embeddedness of the Terms in the Major Sections of the Regulations

The analysis of the frequency of the terms referred to in the three documents based on their major structural sections, namely the preamble, objectives, permitting, risk assessment, monitoring, and governance sections, as represented in Figure 2, reveals interesting results.

Most of the terms related to water drivers, “drought” and “scarcity”, are mainly referred to in the preamble of the three regulations, which have no force of law. Still, in the EU and Spanish regulations, “scarcity” also appears in the objectives section. In the EU regulation, the embeddedness of spatial terms is strong in the preamble, followed by the objectives and risk assessment sections. In contrast, in the Portuguese regulation, the spatial terms are mostly referred to in the scope and objectives, permitting, and monitoring sections. This document has no references to spatial concerns in the governance and public engagement section. The Spanish regulation shows spatial terms primarily in the objectives, permitting, and risk assessment sections. It also includes a few references in the governance and public engagement section, in contrast with the EU and the Portuguese regulations, in which they are scarcely mentioned. Regarding activities and land use types, the EU regulation mainly includes these terms in the preamble and objectives, with “urban” and “agriculture” appearing across all sections. In the Portuguese regulation, these terms are distributed among the different sections of the document. The Spanish regulation also refers to these terms in most sections, except for “forest”, which is only mentioned in the monitoring section. The references to activities in the governance and public engagement section are higher than those in the other regulations.

Table 4. Main key regulatory contrasts among the regulations.

	EU	Portugal	Spain
Water Driver	Scarcity and drought	Drought	Water availability, scarcity
Spatial Concerns	Plan, area, local	Local, transport	Plan, river basin, wetland
Land Uses	Agriculture, urban	Industry, green areas, forest	Urban, green areas
Section Focus	Introduction Objectives and scope Risk assessment	Permitting, compliance and enforcement Monitoring and quality standards	Monitoring and quality standards Risk assessment Governance and public engagement

summarises the major key regulatory contrasts.

5. Discussion

This section discusses the key findings considering the research question (Are spatial concerns integrated into the water reuse regulations? If yes, how do the patterns of this integration compare between different country regulations?) and the quality of the findings, considering the methodology and their added value to the broader scientific community and regulators.

5.1. The Data, the Method, and the Findings

Water reuse regulations should account for the critical influence of location and land use on water production and availability and recognise the need to engage a broad range of stakeholders, including land and water users. At the EU level, water reuse regulations establish minimum standards for reclaimed water; the land uses and activities involved; and guidance for permitting, risk management and monitoring. At the member state levels, regulations derive from the general requirements and translate them into national and territorial specificities. Their narrative is influenced by institutional, administrative, and political traditions and cultural contexts, which were not considered in this article. The analysis of the regulations focused on substantive terms, which were searched through a systematic quantitative and qualitative method to assess the embeddedness of water scarcity, spatial terms, and land use types. This analysis of the overall embeddedness was performed mainly by counting the frequency of specific words or content to understand their contextual use [54]. The assessment of the distribution in the different sections of the regulation is complex and prone to error since the structure of the documents varies. To avoid misinterpretation of the texts, the different authors who cross-read the documents checked the content analysis. Also, the analysis was undertaken on regulations translated to English, facilitating the comparison yet missing the particularities of each mother language, likely to be lost after the translations. The analysis covered the EU and the two countries of the Iberian Peninsula, a territory vulnerable to drought events and facing water scarcity problems. It offered interesting insights into the different regulatory approaches regarding the inclusion of spatial concerns. Extending this study to other countries could offer new and valuable insights into spatial-wise water reuse regulations.

While the integration between land use and water resource planning is acknowledged as essential in the literature [8,12], the findings show that the integration of spatial concerns is present, though in tiny proportions, in the narrative and with different approaches within each regulatory analysed document. The comparative analysis of the EU, Portuguese, and Spanish regulations highlights notable differences in regulatory approaches regarding the inclusion of spatial concerns. The EU and Spanish regulations emphasise a long-term imbalance between water supply and demand. In contrast, Portugal uses more the perspective of a temporary phenomenon caused by reduced rainfall. This distinction indicates differences in how each regulation perceives and responds to these challenges. The Portuguese regulations, dating from 2019, precede the EU regulations, emerging as a regional response to severe drought events and the need to reduce freshwater consumption. While it aligns with earlier EU directives like Directive 91/271/EEC on urban wastewater treatment, it lacks the harmonised criteria and cross-border coherence established by the 2020 EU regulation. This temporal difference also explains the limited emphasis on integrated risk management and the need for future updates to enhance alignment. The Spanish regulations, approved after that of the EU, mirror the perspectives of the EU on this long-term planning perspective. The stronger integration of broad spatial concerns in the Portuguese regulations suggests a stronger connection to land use planning. The Spanish regulations, however, stress more the need to consider the river basin in the context of water reuse, reinforcing a hydrological approach. While agriculture and urban activity uses are the most frequently referenced across all regulations, showing their importance in water reuse strategies, Portugal also places a stronger emphasis on industry and green areas than the EU and Spain. Also, Spain strongly focuses on ecological and environmental concerns, referring more to forests and wetlands. While spatial concerns are mainly addressed in the EU regulations’ objectives and risk management sections, they are more widely distributed in the various sections of Portugal’s and Spain’s regulations. Portugal has a prominent presence in the permitting and monitoring sections, while Spain is also prominent in risk assessment. Similar results are evident in the references to land uses and activities. Moreover, spatial concerns are mainly addressed in the EU regulations’ objectives and risk management sections, but they are more widely distributed in the various sections of Portugal’s and Spain’s regulations. Yet, Portugal’s regulations are prominent in the permitting and monitoring sections, while Spain is also prominent in risk assessment. Similar results are evident in the references to land uses and activities. No specific references to spatial planning or spatial plans were found in any of the analysed water reuse regulations.

5.2. The Findings and the Literature

This study advances the discourse on land-water governance by bridging the gap between water reuse regulatory analysis and spatial planning. While prior research has predominantly focused on water reuse’s technical and hydrological dimensions, this study highlights the spatial and regulatory dimensions, addressing a key gap in the literature [49,55]. It emphasises the need for enhanced policy coordination, explicit spatial frameworks, and the adoption of integrated tools (e.g., territorial zoning) that align water reuse with water scarcity, ecological, and spatial planning priorities [21,41]. Given that water availability and production are influenced by land use and spatial concerns [41], the incorporation of these spatial considerations into water reuse regulations necessitates integrating water scarcity and reuse into planning instruments, ensuring that land use activities enhance both water quality and quantity, and fostering synergies between water protection and spatial planning measures [9,19,20]. To this end, it is essential to tailor water reuse policies to regional hydrological, climatic, and infrastructural conditions while integrating zoning and permitting procedures for effective land-water governance [19,41,44]. However, this requires a thorough understanding of the local contexts and regulatory frameworks, calling for guidance about context-based solutions that account for territorial specificities. Effective policies must adapt to regional water stress levels, existing governance structures, and land use patterns to ensure the enforceability and sustainability of water reuse initiatives [20,23,49]. Furthermore, the findings emphasise that effective integration requires coordination across multiple government levels and agencies [19,41]. The findings can also be discussed through the lens of IWRM and adaptive governance, two key frameworks for environmental governance [13]. The EU regulations (EU 2020/741) reflect IWRM by promoting coherence across water use, land use, and sustainability through standardised risk management and cross-sectoral coordination. Portugal’s regulations, developed earlier, follow a more sectoral approach, focusing on specific reuse, disregarding an IWRM approach. In contrast, Spain’s regulations are more aligned with adaptive governance principles, emphasising public participation, multi-level coordination, and stakeholder engagement, making it more flexible and responsive to diverse interests and changing conditions. Moreover, Portugal’s regulations do not explicitly reference public engagement mechanisms, which may limit transparency, reduce community involvement, and weaken the legitimacy of water reuse initiatives. In contrast, Spain’s regulations include provisions for public information, awareness campaigns, and stakeholder participation, reflecting a more participatory governance approach [13,15,16]. This difference highlights how governance design can directly influence the acceptance and sustainability of water reuse practices.

Based on our findings, water reuse regulations may be strengthened by requiring zoning overlay checks for the location of water reuse projects, with due consideration for the functioning of the river basin, related hydrological units, and ecological water flows. Incorporating spatial concerns into permitting processes, as seen in the EU and Portugal, may also ensure alignment with land use and water quality protection. Additionally, technical guidance for infrastructure location, inspired by Portugal’s planning approach, may enhance regulatory clarity. Strengthening monitoring protocols and stakeholder engagement, particularly in drought-prone areas, mirrors Spain’s commitment to public participation. Finally, regulations should incorporate ecosystem-sensitive planning, as exemplified by the EU and Spain, to protect critical areas like wetlands and river basins.

Ensuring adequate inclusion of spatial concerns into water reuse regulations requires policy efforts that align land use and water reuse strategies, particularly through risk-based permitting, spatial planning tools, and governance coordination. Future research should broaden the scope of regulatory comparisons to include additional countries and examine real-world implementation while also exploring the factors that influence the integration of spatial concerns and land use planning in water reuse regulations to generate deeper insights for more effective and climate-resilient water governance.

6. Conclusions

Water reuse regulations are emerging, but little is known about the integration of scarcity and spatial concerns into their contents. Through a systematic content analysis, this article reveals significant differences in the embeddedness of the concerns in the EU, Portugal, and Spain water reuse regulations. The findings of this article offer valuable contributions to both the scientific community and regulatory bodies by revealing the varying approaches to integrating spatial concerns within water reuse regulations across different jurisdictions. By emphasising the disparities between the European Union, Portugal, and Spain, this research not only highlights how these regulations address the fundamental challenge of water scarcity but also underscores the importance of contextual considerations in policymaking. The identified differences, such as Portugal’s orientation towards land use planning and Spain’s ecological focus, unveil how national options and characteristics influence water management regulatory strategies. This insight can help foster more effective regulatory frameworks that are responsive to local water scarcity issues and environmental contexts. For regulators, these findings serve as a valuable resource for enhancing policy efficacy related to water reuse. By revealing the prominence of spatial concerns in specific regulatory sections, such as permitting and risk assessment, this study encourages regulators to adopt a more holistic approach when crafting laws. The emphasis on integrating land use considerations into water management can guide the development of more sustainable and adaptive policies that balance socio-economic demands with ecological preservation. Furthermore, the comparative analysis highlights best practices that can be shared and adapted among jurisdictions, promoting collaboration and knowledge exchange aimed at achieving water resource sustainability in the face of growing climate challenges.