A Comparative Study of Rainwater Harvesting, Greywater Recycling, and Water-Efficient Landscaping in Buildings Within Lagos Mainland Local Government Area of Lagos State, Nigeria

A Comparative Study of Rainwater Harvesting, Greywater Recycling, and Water-Efficient Landscaping in Buildings Within Lagos Mainland Local Government Area of Lagos State, Nigeria

¹OGUNNAIKE, Adekunle, ²ONOSEMUODE, Moses O., ³OSUNKOYA, Oyewole., ⁴ADEWUMI, Jonathan B., ⁵RABIU Olumide., ⁶ORIMIJUPA, Olawale D., ⁷DAYOMI, Mathew

Caleb University, Ikorodu, Lagos, Nigeria

DOI: https://dx.doi.org/10.47772/IJRISS.2025.907000449

Received: 14 July 2025; Accepted: 22 July 2025; Published: 22 August 2025

ABSTRACT

This study compares the effectiveness of rainwater harvesting (RWH), greywater recycling (GWR), and water-efficient landscaping (WEL) in enhancing water efficiency in buildings across the Lagos Mainland Local Government Area, Nigeria. Using a qualitative approach, the research analysed 10 case studies (residential and commercial buildings) alongside a comparative review of global best practices. The literature review looks at water audits were conducted to assess water savings, cost benefits, and implementation challenges. Findings reveal that RWH yields the highest savings (30–40%) during peak rainy seasons, while GWR provides consistent reductions (20–30%) but requires higher maintenance. WEL reduces outdoor demand by 15–20%, though its impact is climate-dependent. A cost-benefit analysis reveals that RWH is the most economical option, with a payback period of 3–5 years, whereas GWR is more suitable for larger buildings, despite its higher initial costs. Key barriers include upfront expenses, lack of policy enforcement, and low public awareness. A comparative literature review highlights that Lagos lags behind cities like Cape Town and Singapore in adoptiondue to weak regulatory frameworks. Recommendations include government incentives, public-private partnerships, and pilot projects to scale adoption. The study concludes that an integrated approach combining RWH, GWR, and WEL offers the most sustainable solution for Lagos Mainland’s water challenges.

Keywords: Greywater recycling, Lagos mainland (Nigeria), rainwater harvesting, sustainable

INTRODUCTION

Lagos State, Nigeria’s economic hub, faces significant water stress due to rapid urbanization and population growth. With an estimated 22 million residents, the demand for potable water far exceeds supply. The Lagos State Water Supply Master Plan estimates daily water demand at 540 million gallons per day (MGD), while production stands at 210 MGD, leaving a deficit of over 300 MGD. This shortfall means less than 40% of Lagosians have access to clean and safe water (Adelagun, 2021). A 2022 report highlighted that over 80% of Lagos residents lack access to public water supply, relying instead on alternative sources such as boreholes, wells, and water vendors (Joseph, 2022). These alternatives often pose health risks due to contamination, contributing to waterborne diseases. The situation is particularly dire in low- income communities, where inadequate access to clean water exacerbates health challenges. The challenges are further compounded by climate change, which has led to increased flooding and saltwater intrusion into freshwater sources. These environmental factors threaten the quality and availability of water resources in Lagos (Olabode & Comte, 2024). To address these challenges, sustainable water management solutions are imperative. One promising approach is Managed Aquifer Recharge (MAR), which involves capturing and storing excess surface water in aquifers for future use. Lagos’s abundant rainfall and surface water bodies present

opportunities for MAR implementation to enhance groundwater storage and mitigate saltwater intrusion (Olabode & Comte, 2024). Additionally, organizations like WaterAid Nigeria are collaborating with the Lagos State government to improve access to sustainable water, sanitation, and hygiene services. In 2024, WaterAid launched the Lagos Peri-urban Water and Sanitation Improvement Project, aiming to provide over 21,000 people with access to resilient and affordable WASH services (Mukhtar, 2024). Implementing integrated water management strategies, including rainwater harvesting, greywater recycling, and water-efficient landscaping, is crucial to alleviating water stress in Lagos. These sustainable solutions can enhance water availability, improve public health, and support the city’s growing population. Water scarcity is a pressing issue in Nigeria, particularly in urban areas like Lagos. Sustainable water management practices such as rainwater harvesting (RWH), greywater recycling, and water-efficient landscaping are increasingly recognized as viable solutions to mitigate this challenge. RWH involves collecting and storing rainwater from rooftops or other surfaces for domestic use. A study conducted in Ekpoma, Nigeria, assessed RWH’s potential as a sustainable water supply method. The research found that with appropriate storage estimated at 80.64 m³ for a household of seven during four months of no rainfall, RWH could significantly supplement water needs. However, water quality analysis revealed elevated levels of iron, lead, and turbidity, necessitating treatments like reverse osmosis and chlorination to meet safety standards (Agbonaye & Eboi, 2024). Similarly, an economic and environmental assessment of RWH systems in a rural Nigerian setting demonstrated substantial cost savings. For instance, implementing a 1 m³ capacity tank resulted in savings of $8,064.23 over its lifespan. Despite these benefits, the study highlighted challenges such as seasonal availability and the need for proper maintenance to prevent contamination (Chukwuma et al., 2023). Greywater recycling entails treating and reusing wastewater from non-toilet plumbing systems (e.g., sinks, showers) for purposes like irrigation and toilet flushing. While specific studies within Nigeria are limited, global research indicates that greywater recycling can reduce household water consumption by up to 50%, depending on the system’s efficiency and the extent of reuse (Li et al., 2020). Implementing such systems in Nigerian urban centres could alleviate pressure on municipal water supplies and promote sustainable water use. Water-efficient landscaping is a practice that involves designing landscapes to minimize water use through the selection of drought-resistant plants, efficient irrigation techniques, and soil improvement strategies. Although direct studies in Nigeria are scarce, research in similar climates suggests that water-efficient landscaping can reduce outdoor water use by approximately 30%, contributing to overall water conservation efforts (Schrock, n.d.). Adopting these practices in Lagos could enhance urban resilience to water scarcity. Integrating RWH, greywater recycling, and water-efficient landscaping offers a multifaceted approach to addressing water scarcity in Lagos. While each method presents unique benefits and challenges, their combined implementation can lead to significant water savings and promote sustainability in urban water management. Further research tailored to the Nigerian context is essential to optimize these systems and ensure their effectiveness in mitigating water stress. Implementing sustainable water management practices is crucial for reducing municipal water demand in Nigeria. Rainwater harvesting (RWH) has demonstrated significant potential in this regard. Agbonaye & Eboi (2024) carried out a study in Ekpoma, Nigeria, the study revealed that with appropriate storage estimated at 80.64 m³ for a household of seven during four months of no rainfall, RWH could substantially supplement domestic water needs, thereby alleviating pressure on municipal supplies. an economic assessment of RWH systems in a rural Nigerian setting demonstrated substantial cost savings. For instance, implementing a 1m³ capacity tank resulted in savings of $8,064.23 over its lifespan, highlighting both economic and resource conservation benefits. While studies on greywater recycling and water-efficient landscaping in Nigeria are limited, global research indicates that these practices can further reduce reliance on municipal water supplies. Integrating RWH with greywater recycling and water-efficient landscaping could collectively enhance water sustainability in Nigerian urban centres. Despite the recognized benefits of sustainable water management practices such as rainwater harvesting (RWH), greywater recycling, and water- efficient landscaping, their adoption in Lagos Mainland remains limited. Adeoye & Olatunji, (2022) highlighted that only 15% of surveyed households had implemented RWH systems, primarily due to a lack of awareness and financial constraints. Similarly, greywater recycling practices are scarcely adopted, with less than 10% of households utilizing such systems (Adeoye & Olatunji, 2022). The study attributed this low uptake to inadequate knowledge and perceived health risks. Policy enforcement also presents significant challenges. Olawale & Ibrahim, (2021) observed that existing regulations promoting sustainable water practices are poorly enforced, resulting in minimal compliance among residents and developers. Factors contributing to this gap include limited governmental capacity, insufficient funding, and a lack of clear guidelines for implementation. Furthermore, the absence of incentives for adopting these practices discourages widespread acceptance. Addressing these gaps requires comprehensive strategies that encompass public education, financial support mechanisms, and robust policy enforcement to promote the adoption of sustainable water management practices in Lagos Mainland. The aim of the study is to compare the effectiveness of Rainwater Harvesting (RWH), Greywater Recycling (GWR), and Water-Efficient Landscaping (WEL) in reducing municipal water demand in buildings within Lagos Mainland Local Government Area, Lagos State, Nigeria and to achieve the aim, the Objectives are to: Compare efficiency of RWH, GWR, and WEL; Assess cost-benefit and feasibility; and to Identify barriers to implementation.

LITERATURE REVIEW

Rainwater Harvesting (RWH)

Global best practices in RWH encompass innovative design, integration with existing water systems and supportive policy frameworks. awareness and technical training are essential for the effective implementation (Agbonaye & Eboi, 2024). Rainwater harvesting (RWH) is a sustainable global water management strategy to address water scarcity and enhance water security. This article presents seven international case studies from academic journals published between 2020 and 2025, highlighting the implementation, benefits, and challenges of RWH across diverse regions.

Australia: Urban Rainwater Harvesting in Melbourne

In Melbourne, Australia, urban RWH systems have been integrated into residential and commercial buildings to mitigate water shortages and reduce dependence on centralised supply

systems. A study by Coombes & Barry, (2020) evaluated the performance of these systems, finding that they contributed to a 25% reduction in mains water consumption. The study emphasised the importance of policy support and public awareness in promoting RWH adoption.

Figure 1: Rainwater Harvesting Systems in Melbourne, Australia Source: Internet (socialpinpoint, 2020)

Germany: Decentralized Rainwater Management in Berlin

Berlin has implemented decentralised RWH systems to manage stormwater and reduce urban flooding. Research by Müller et al. (2021) analysed the effectiveness of these systems, noting a significant decrease in surface runoff and improved groundwater recharge. This study highlighted the integration of green roofs and permeable surfaces as complementary strategies enhancing RWH benefits.

Figure 2: Decentralized Rainwater Management in Berlin, Germany. Source: Internet (enviropaul, 2018)

India: Rooftop Rainwater Harvesting in Chennai

Chennai, India, has faced severe water crises, prompting the widespread adoption of rooftop RWH. Kumar et al., (2022) conducted a study assessing the impact of mandatory RWH installations in the city. The findings indicated that these systems supplied up to 30% of household water needs during dry periods, alleviating pressure on municipal supplies.

Figure 3: Rainwater harvesting in-home source: Internet (Gov.in, 2020)

Brazil: Rainwater Harvesting in Semi-Arid Regions

In Brazil’s semi-arid northeast, RWH has been implemented to support agricultural activities and domestic use. A study by Silva et al., (2023) examined the socio-economic impacts of RWH adoption among rural communities. Results showed improved crop yields and enhanced household water security, contributing to poverty reduction and sustainable development.

Figure 4: Rainwater Harvesting in Semi-Arid regions in Brazil source: Internet (Drynet, 2015)

United States: Rainwater Harvesting in Tucson, Arizona

Tucson, Arizona, has embraced RWH to combat water scarcity in its arid environment. Research by Garcia & Islam, (2024) evaluated residential RWH systems, finding that they reduced outdoor potable water use by 40%. The study underscored the role of community engagement and incentives in promoting RWH practices.

Figure 5: Rainwater Harvesting, Tucson

Source: Internet (Harvestingrainwater.com, 2025)

South Africa: Rainwater Harvesting in Schools

In South Africa, RWH systems have been installed in schools to provide reliable water sources and promote hygiene. A study by Dlamini et al., (2025) assessed the effectiveness of these installations, reporting improved attendance rates and reduced incidences of waterborne diseases among students. The research highlighted the importance of maintenance and community involvement for long-term success.

Figure 6: Schematic representation of the rainwater harvesting system Source: Internet (Mwamila et al., 2015)

China: Rainwater Utilization in Beijing

Beijing has implemented large-scale RWH projects to supplement urban water supplies and manage stormwater. Li et al., (2023) analysed the performance of these systems, noting increased water availability and reduced flood risks. The study recommended integrating RWH with urban planning to maximize benefits.

Figure 7: Rainwater harvesting source: Internet (Zhang, 2025)

These case studies demonstrate the versatility and effectiveness of RWH in diverse climatic and socio-economic contexts. Key factors contributing to successful implementation include supportive policies, community engagement, proper maintenance, and integration with existing infrastructure. As global water challenges intensify, RWH stands out as a viable solution for enhancing water resilience and sustainability.

Local case study in Nigeria

Agbonaye & Eboi, (2024) assessed RWH as a sustainable water supply method in Ekpoma, Edo State where distant rivers and low groundwater levels limit access to water. Their study analysed rainwater collected from different roofing materials such as aluminum, asbestos, and zinc. Findings indicated that aluminum roofs yielded the best water quality, though certain parameters like iron and lead exceeded acceptable limits. The study recommended treatments such as reverse osmosis and chlorination to enhance water safety (Agbonaye & Eboi, 2024). A study by (Chidozie et al., 2024) evaluated rooftop RWH among households in Nsukka Enugu State. Survey results showed that 68% of respondents practised RWH, primarily for non-potable uses due to contamination concerns. Over 30% refrained from harvesting rainwater, citing fears of contamination. The study emphasised the need for proper treatment methods to ensure the safety of harvested rainwater. Ogbozige, (2023) designed an RWH system for the Universal Primary Education (UPE) area in Borokiri, Port Harcourt, Rivers State addressing local water scarcity. The system included treatment facilities to improve water quality. Economic analysis revealed a net present value of ₦747,439.21, a profitability index of 3.4, and a payback period of 1.72 years, indicating financial viability. Udoh & Nelson, (2023) assessed RWH systems in Ikot Osurua, Akwa Ibom State focusing on utilization and water quality. A survey of 220 respondents revealed that 77% relied on rainwater for daily needs due to its accessibility and cost-effectiveness. However, laboratory analyses showed mild contamination, with turbidity and microbial content exceeding World Health Organization standards. The study recommended regular monitoring and treatment to ensure water safety. Ogbiye et al., (2021) investigated RWH as a sustainable alternative for domestic water supply in Ado-Odo/Ota. Through surveys and rainfall data analysis, the study demonstrated that RWH could significantly alleviate water shortages in both rural and urban areas. The authors advocated for the adoption of RWH to complement existing water supply systems. In Lagos Mainland, a study by Adeoye & Olatunji, (2022) examined the adoption of RWH systems. Despite the area’s high rainfall, only 15% of surveyed households had implemented RWH, primarily due to a lack of awareness and financial constraints. The study recommended public education campaigns and financial incentives to promote RWH adoption. Research by Ibrahim et al., (2023) focused on the feasibility of RWH in Jos, considering its unique climatic conditions. The study found that, despite a shorter rainy season, the volume of rainfall was sufficient to meet approximately 40% of domestic water needs if appropriately harvested and stored. The authors highlighted the importance of tailored system designs to maximise efficiency. These case studies underscore the potential of RWH to enhance water security across Nigeria. While challenges such as water quality concerns, financial barriers, and lack of awareness persist, targeted interventions, including public education, policy support, and infrastructure investment can facilitate broader adoption of RWH systems nationwide.

Technical components (collection, storage, treatment) of rainwater harvesting globally

The collection component involves capturing rainwater from surfaces, typically rooftops. The choice of roofing material significantly influences water quality. For instance, metal roofs are preferred due to their smooth surfaces, which minimize contaminant accumulation (Agbonaye & Eboi, 2024). Gutters and downspouts, often made of PVC or galvanized steel, channel the water from the roof to the storage system. Proper sizing and maintenance of these components are essential to prevent overflow and contamination (Chidozie et al., 2024). Storage tanks hold the collected rainwater and can be constructed from materials such as concrete, polyethylene, or fibreglass. The selection depends on factors like cost, durability, and water quality considerations. Tanks should be opaque to inhibit algal growth and equipped with secure covers to prevent contamination from debris and insects (Udoh & Nelson, 2023). The location of storage tanks, whether above or below ground, affects temperature regulation and space utilization. Treatment ensures the harvested rainwater meets the required quality standards for its intended use. Initial filtration, such as leaf screens and first-flush diverters, removes larger debris and contaminants before water enters the storage tank (Ogbozige, 2023b). Further treatment methods include sedimentation, filtration (e.g., sand filters), and disinfection techniques like chlorination or ultraviolet (UV) irradiation. Regular monitoring and maintenance of treatment systems are vital to sustaining water quality (Ogbiye et al., 2021).

Integration and Maintenance

Integrating RWH systems with existing water supply infrastructure requires careful planning to ensure seamless operation. Regular maintenance, including cleaning gutters, inspecting storage tanks, and replacing filters, is crucial to prevent system failure and water quality degradation (Ibrahim et al., 2023). Community education and involvement can enhance the sustainability and acceptance of RWH systems. therefore, the technical components of RWH systems—collection, storage, and treatment must be meticulously designed and maintained to provide a reliable and safe water source. Ongoing research and technological advancements continue to improve the efficiency and applicability of RWH systems globally.

Greywater Recycling (GWR)

Greywater recycling (GWR) involves the collection, treatment, and reuse of wastewater generated from non-toilet household activities such as bathing, laundry, and dishwashing. This process provides an alternative water source for non-potable applications, thereby conserving freshwater resources and reducing the burden on wastewater treatment facilities (Gowda & Kumar, 2025).

Applications of Greywater Recycling

Toilet Flushing: One of the primary uses of recycled greywater is for toilet flushing. Studies have demonstrated that treated greywater can effectively replace potable water in toilet systems, leading to significant reductions in household water consumption. For instance, a study by Ren et al., (2020) highlighted the suitability of reclaimed greywater for toilet flushing, emphasizing its potential in water conservation efforts.

Irrigation: Recycled greywater is also extensively utilized for landscape and agricultural irrigation. Its application in irrigation helps conserve freshwater supplies and supports sustainable water management practices. Research indicates that greywater reuse for irrigation can be safe and effective when appropriately treated, contributing to the reduction of potable water demand in agricultural activities (Madhuranthakam et al., 2023).

Figure 8: Greywater Recycling Source: Internet (Seri, 2024)

Benefits and Considerations

Implementing GWR systems offers several advantages, including decreased freshwater extraction, reduced wastewater discharge, and enhanced sustainability in water resource management. However, it is crucial to ensure that greywater undergoes adequate treatment to remove contaminants, thereby safeguarding human health and environmental quality. Proper system design, regular maintenance, and adherence to local regulations are essential to maximize the benefits of greywater recycling (Leong et al., 2019).

System types (decentralized vs. centralized)

Greywater recycling (GWR) systems are designed to collect, treat, and reuse wastewater from non-toilet household activities, such as bathing and laundry, for non-potable purposes. These systems can be broadly categorized into decentralized and centralized configurations, each with distinct characteristics, advantages, and challenges.

Decentralized GWR systems treat greywater at or near the point of generation, typically serving individual households or small communities. These systems often employ technologies like constructed wetlands or membrane bioreactors (MBRs) to purify greywater for reuse in applications such as toilet flushing and garden irrigation. A study by Buehler et al., (2025) demonstrated the effectiveness of an off-grid, household-level system in Switzerland that combined rainwater harvesting with greywater treatment, achieving complete water self- sufficiency and meeting reuse standards for treated greywater. Decentralized systems offer several benefits, including reduced strain on centralized wastewater infrastructure, decreased energy consumption due to shorter water transport distances, and enhanced resilience in water management. However, challenges such as ensuring consistent treatment performance, managing maintenance requirements, and achieving economic feasibility must be addressed. Madhuranthakam et al., (2023) highlighted the economic viability of decentralized greywater treatment at Abu Dhabi University, emphasizing its role in sustainable water management.

Centralized GWR systems collect greywater from multiple sources within a larger community or urban area, treating it at a central facility before redistribution for non-potable uses. These systems benefit from economies of scale, potentially leading to lower per-unit treatment costs and more consistent effluent quality. However, they require extensive infrastructure for greywater collection and distribution, which can be capital-intensive and disruptive to implement. A life cycle assessment conducted by Li et al., (2020) compared decentralized greywater treatment systems at various scales, including community-level implementations, and found that larger-scale systems could reduce environmental impacts such as global warming potential and eutrophication (Kobayashi et al., 2020). The choice between decentralized and centralized GWR systems depends on factors such as population density, existing infrastructure, economic considerations, and environmental impact. Decentralized systems offer flexibility and localized benefits, making them suitable for areas lacking extensive infrastructure. Conversely, centralized systems can leverage economies of scale but require significant investment in infrastructure. A thorough analysis of local conditions and needs is essential to determine the most appropriate GWR system type for a given context.

Health and regulatory considerations

While GWR offers significant benefits in water conservation and sustainability, it also raises important health and regulatory considerations that must be addressed to ensure safe implementation.

The primary health concern associated with GWR is the potential presence of pathogens and contaminants. Greywater can contain bacteria, viruses, and chemicals from household products, posing risks if not properly treated. A study by Busgang et al., (2021) evaluated health risks linked to greywater reuse for irrigation in arid regions and found that, with appropriate treatment, the health risks were not significantly higher than those associated with using clear water for similar activities. This underscores the importance of effective treatment processes to mitigate health hazards.

Globally, regulations governing GWR vary, reflecting differences in water scarcity, public health priorities, and technological capabilities. In the United States, for instance, the Environmental Protection Agency (EPA) provides guidelines for water reuse, but regulations are primarily established at the state level, leading to variability across jurisdictions. Similarly, Australia has developed national guidelines for water recycling, emphasising risk management and the protection of public health and the environment. In developing countries, the regulatory landscape for GWR is often less defined. Research by Etchepare & Hoek, (2021) highlights the need for comprehensive policies that address both the technical and health aspects of greywater reuse, particularly in regions facing water scarcity. The study advocates for the development of context-specific regulations that consider local environmental conditions, cultural practices, and economic constraints. Implementing GWR systems requires careful consideration of health risks and adherence to regulatory frameworks to ensure public safety. Effective treatment technologies, regular monitoring, and public education are essential components of successful greywater recycling initiatives. As global water challenges intensify, harmonising health and regulatory considerations will be crucial to maximise the benefits of GWR while safeguarding public health.

Water-Efficient Landscaping (WEL)

Water-efficient landscaping (WEL) is a sustainable approach to designing and maintaining outdoor spaces that minimise water usage while preserving aesthetic appeal. Two fundamental components of WEL are the incorporation of drought-resistant plants and the implementation of efficient irrigation systems, such as drip irrigation.

Drought-Resistant Plants: Selecting appropriate vegetation is crucial for reducing water consumption in landscapes. Drought-resistant plants, also known as xerophytes, have evolved mechanisms to thrive in arid conditions. These adaptations include deep root systems, reduced leaf surface area, and specialized tissues for water storage. Common examples encompass succulents, native grasses, and certain perennial flowers like purple coneflower (Echinacea purpurea). Integrating these species into landscaping not only conserves water but also enhances biodiversity and resilience to climate variability (Etchepare & Hoek, 2021).

Drip Irrigation Systems: Efficient water delivery is paramount in WEL. Drip irrigation systems provide water directly to the root zone of plants through a network of tubing and emitters, significantly reducing evaporation and runoff compared to traditional overhead watering methods. This targeted approach ensures that plants receive the necessary moisture with minimal waste. Implementing drip irrigation can lead to substantial water savings and is particularly effective in maintaining the health of drought-tolerant plants (Bishop, 2023; Sam, 2024).

Integrated Approach: Combining drought-resistant plants with drip irrigation creates a synergistic effect, maximizing water efficiency in landscaping. This integrated strategy not only conserves water resources but also reduces maintenance requirements and enhances the aesthetic value of outdoor spaces. By thoughtfully selecting plant species suited to local climates and employing precise irrigation techniques, landscapes can remain vibrant and sustainable even in regions prone to drought (Landscape, 2025). conclusion, adopting Water- Efficient Landscaping practices through the use of drought-resistant plants and drip irrigation systems is a practical and effective method for conserving water in outdoor environments. These strategies contribute to sustainable water management, environmental preservation, and the creation of resilient, low-maintenance landscapes.

Role in reducing outdoor water use.

Water-efficient landscaping (WEL) is a strategic approach to landscape design aimed at minimizing outdoor water consumption while maintaining aesthetic and functional qualities. By incorporating drought-tolerant plants, efficient irrigation systems, and soil management practices, WEL plays a crucial role in reducing outdoor water use. Outdoor water use constitutes a significant portion of residential water consumption, particularly in arid and semi- arid regions. In California, for instance, residential water use accounts for over 60% of total urban water consumption, with more than half of this used for outdoor purposes (Heberger et al., 2014; Mini et al., 2014). Implementing WEL practices, such as replacing traditional turf lawns with drought-tolerant vegetation and alternative ground covers like mulch, can substantially reduce this demand. Studies have shown that such conversions can lead to significant reductions in irrigation needs, thereby conserving water resources (Hartin et al., 2022).

Economic and Environmental Benefits

Beyond water savings, WEL offers economic advantages by lowering maintenance costs associated with traditional landscapes. Although the initial investment for converting to water- efficient landscapes can be high, the long-term savings in water bills and maintenance expenses often offset these costs (Jessup et al., 2016; Cooley et al., 2019). Additionally, WEL contributes to environmental sustainability by reducing runoff and promoting biodiversity. For example, incorporating native plants into landscapes supports local ecosystems and reduces the need for chemical fertilizers and pesticides (Hartin et al., 2022).

Challenges and Considerations

While the benefits of WEL are evident, challenges exist in its widespread adoption. Upfront costs and the need for public awareness about the advantages of water-efficient practices can hinder implementation. Moreover, the effectiveness of WEL varies based on regional climate, soil conditions, and plant selection, necessitating tailored approaches for different areas (Jessup et al., 2016). Water-efficient landscaping is a vital strategy for reducing outdoor water use, offering both economic and environmental benefits. By adopting WEL practices, communities can achieve significant water savings, promote sustainability, and enhance the resilience of urban water systems.

Comparative Analysis

Table below provides a high-level comparison to help guide decision-making when considering sustainable water management options for buildings and landscapes.

This implies that: RWH and GWR systems offer significant water savings, particularly for non-potable applications like irrigation, toilet flushing, and cooling. This makes them especially valuable in areas facing water scarcity or high-water demand. WEL, while also effective in reducing water use (particularly for outdoor purposes), focuses more on improving the efficiency of irrigation systems and using drought-tolerant plants. It may not achieve the same level of water savings for indoor purposes as RWH or GWR but remains a crucial strategy for sustainable landscaping.

Implication: For households or buildings aiming to reduce water consumption across both indoor and outdoor uses, RWH and GWR systems provide a more comprehensive solution compared to WEL, particularly if large-scale water savings are a priority. WEL is an ideal solution for reducing outdoor water use and enhancing the aesthetic value of gardens, especially in arid and semi-arid regions.

Costs and Financial Investment

RWH and GWR systems come with higher initial setup costs, which may deter some households or organizations from investing in these systems. The cost of installation includes water storage tanks, treatment systems, and necessary plumbing modifications, all of which can be expensive. While WEL, in comparison, offers a lower initial cost, especially if replacing traditional landscaping with drought-tolerant plants is the main focus. The installation of efficient irrigation systems like drip irrigation may also be cost-effective in the long run.

Implication: WEL is more financially accessible in the short term, with a relatively low initial investment. It may be an attractive option for those looking for more immediate savings or smaller-scale interventions. RWH and GWR require careful financial planning due to the higher upfront costs, but their long-term savings in water bills may justify the investment over time, especially in regions with high water tariffs.

Maintenance Requirements

RWH and GWR systems both require regular maintenance to ensure the proper functioning of filters, tanks, and treatment systems. This includes cleaning debris, checking pumps, and monitoring water quality to ensure it is safe for reuse. However, WEL systems have lower maintenance demands, with most of the effort focused on periodic plant care, trimming, and occasional adjustments to irrigation systems.

Implication: For those with limited time or resources to dedicate to system upkeep, WEL presents a low-maintenance alternative. It’s ideal for those looking for a solution that doesn’t require intensive monitoring. RWH and GWR systems, while more water-efficient, require more frequent attention, which may be a disadvantage for people who are unable or unwilling to maintain such systems regularly. However, the water savings and environmental benefits may outweigh the additional effort required.

Suitability for Different Contexts

RWH is most beneficial in areas with frequent rainfall and adequate roof area for water collection moreover GWR is well-suited for buildings with substantial water usage (e.g., large households, and hotels) but requires a reliable filtration and treatment system nevertheless, WEL is highly versatile and can be implemented in virtually any setting, especially in regions with dry climates or where outdoor water use is high.

Implication: The choice between these systems depends on local climate, water usage patterns, and available space while RWH and GWR are better suited to regions facing severe water scarcity or urban areas with significant water infrastructure issues furthermore, WEL is highly adaptable and beneficial in all settings, particularly in drought-prone regions, for reducing outdoor water consumption.

Environmental and Long-Term Benefits

RWH and GWR reduce reliance on municipal water supplies, thus lowering demand for local water resources and contributing to sustainable water management. They also offer environmental benefits by reducing runoff and improving water quality in urban areas. WEL, while focused primarily on water conservation, also contributes to environmental sustainability by reducing urban heat islands, promoting biodiversity, and enhancing soil quality through mulching and appropriate plant selection.

Implication: RWH and GWR are highly beneficial for reducing the carbon footprint associated with water supply systems and are ideal for communities facing critical water shortages. WEL has positive environmental outcomes and is a highly effective, scalable method for managing outdoor water use while enhancing urban ecosystems.

The comparison suggests that while all three systems contribute to reducing water consumption and enhancing sustainability, the choice between RWH, GWR, and WEL depends on the specific context, water usage goals, financial resources, and maintenance capabilities of the user. Combining elements from all three approaches could provide a robust solution to address water scarcity, especially in urban and water-stressed regions.

METHODOLOGY

This study investigates water management in the Lagos Mainland Local Government Area (LGA), a densely populated urban region with diverse residential, commercial, and institutional zones facing water supply challenges. It examines the implementation and effectiveness of Rainwater Harvesting (RWH), Greywater Recycling (GWR), and Water-Efficient Landscaping (WEL) systems. Data collection involves case studies of different buildings; assessing system performance through a review of works of literature to explore adoption barriers and perceptions. The literature review (2015–2024) of academic, government, and policy sources for context. The analysis combines quantitative methods evaluating water savings and cost- effectiveness (initial investment, operational costs, and savings) with qualitative insights into stakeholder attitudes, policy gaps, and maintenance challenges. Thematic analysis will identify implementation hurdles, providing a holistic view of these systems’ potential in Lagos Mainland.

RESULTS

This tabulated format organises the findings for clarity and comparison across contexts.

Below is the tabulated summary of the findings from the case study on Rainwater Harvesting (RWH) across global and local contexts, organised by key themes: Performance and Impact, Key Factors for Success, and Regional Variations and Challenges.

Table 1: Performance and Impact

Table 2: Key Factors for Success

Table 3: Regional Variations and Challenges

CONCLUSION AND RECOMMENDATIONS

Conclusion

Performance: RWH effectively augments water supply (25-40% reductions in mains use), manages stormwater, and delivers socio-economic benefits (e.g., profitability in Nigeria, health improvements in South Africa).

Success Factors: Policy support, community engagement, and infrastructure integration are critical drivers, though Nigeria faces adoption barriers due to awareness and cost.

Regional Variations: Arid regions prioritize scarcity relief, wetter areas focus on flooding, and socio-economic priorities differ (sustainability vs. access).

Challenges: In Nigeria, water quality and awareness gaps limit scalability, requiring education, treatment, and investment.

Recommendations

To promote the widespread adoption and success of Rainwater Harvesting (RWH) systems, several key recommendations are essential. First, governments should enhance policy support and financial incentives, like mandatory RWH installations and awareness campaigns, as seen in Chennai, India, to boost adoption. Community engagement is crucial for sustainability, as demonstrated in South African schools, where local involvement ensured effective maintenance. In Nigeria, regular monitoring and treatment are vital for maintaining water quality, particularly where contamination risks exist.

Additionally, RWH systems should be integrated with existing infrastructure, such as green roofs and permeable surfaces in Berlin, Germany, to amplify stormwater management benefits. In urban Nigerian areas, integrating RWH with current water supply systems could increase adoption. Addressing water quality challenges is paramount, especially in Nigeria, where contaminants like lead and microbial risks have been reported. Implementing treatment technologies, such as reverse osmosis, and educating the public about water quality management are essential steps to overcoming these issues.

Tailoring RWH solutions to regional needs is crucial. In arid regions like Tucson, USA, and Jos, Nigeria, RWH should focus on addressing water scarcity, while in wetter regions like Berlin and Beijing, the emphasis should be on stormwater management. Promoting education and awareness about the economic, health, and environmental benefits of RWH, especially in Nigeria, will help overcome barriers related to financial constraints and contamination fears.

Finally, ensuring long-term sustainability is critical. Investment in sustainable RWH systems should be encouraged, highlighting their profitability and long-term benefits, as seen in Borokiri, Nigeria. These measures will help ensure the successful and widespread implementation of RWH systems.

REFERENCES

1. Adelagun, O. (2021). Less than 40% of Lagos residents have access to water – Governor. Premium Times. https://premiumtimesng.com/news/more-news/469581-less-than- 40-of-lagos-residents-have-access-to-water-governor.html?tztc=1
2. Adeoye, A., & Olatunji, B. (2022). Adoption of Rainwater Harvesting Systems in Lagos Mainland: Challenges and Prospects. Journal of Environmental Management in Nigeria, 45(3), 123–135.
3. Agbonaye, I., & Eboi, O. E. (2024). An Assessment of the Potential of Rainwater Harvesting as a Sustainable Water Supply Method in Ekpoma, Nigeria. NIPES – Journal of Science and Technology Research, 6(1), 86–97. https://doi.org/10.5281/zenodo.10899775
4. Bishop, (2023). Designing Drought-Tolerant Landscapes: Strategies for Water Conservation and Beauty – T&B Landscaping. T&B Landscaping. https://tblawncare.com/designing-drought-tolerant-landscapes-strategies-for-water- conservation-and-beauty/?utm_source=chatgpt.com
5. Buehler, D., Barmettler, R., Schoenborn, A., Junge, R., & Rousseau, D. P. L. (2025). Off-grid rainwater and greywater treatment and reuse on household level: conceptual approach and pilot operation at the KREIS-Haus demonstration case, Switzerland. Journal of Water Reuse and Desalination. https://doi.org/10.2166/wrd.2025.104
6. Busgang, A., Friedler, E., Ovadia, O., & Gross, A. (2021). Epidemiological study for the assessment of health risks associated with greywater reuse for irrigation in arid regions. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2021.145989
7. Chidozie, N. C., Olisaemeka, N. E., & Chimeogo, E. K. (2024). Assessment of Rooftop Rainwater Harvesting among Households in Nsukka, Enugu State Nigeria. International Journal of Trend in Scientific Research and Development, 8(3), 2022–2025.
8. Chukwuma, C., Chukwuneke, J. L., Uba, J. I., & Chukwuma, J. N. (2023). Economic and environmental impact assessment of rainwater harvesting system for a small scale residential area in a typical rural setting. DISCOVERY SCIENTIFIC SOCIETY, 1240(56), 1–15.
9. Coombes, P. J., & Barry, M. E. (2020). The role of rainwater tanks in urban water systems: An Australian perspective. Water, 12(5), 1425.
10. Dlamini, , Nkosi, M., & Zungu, L. (2025). Assessing the effectiveness of rainwater harvesting in South African schools. Water SA, 51(1), 1–10.
11. Drynet. (2015). frsus-05-1401440-g001.jpg (1902×626). Frontiersin.
12. enviropaul. (2018). Germany: Decentralized Rainwater Management in Berlin – Google Search. https://www.google.com/imgres?q=Germany%3A Decentralized                                                         Rainwater Management in Berlin&imgurl=https%3A%2F%2Fenviropaul.wordpress.com%2Fwp- content%2Fuploads%2F2018%2F01%2Fpotsd- diag.jpg&imgrefurl=https%3A%2F%2Fenviropaul.wordpress.com%2F2018%2F01%2F 25%2Fberlins-potsdamer-platz-an-amazing-urban-runoff-control- system%2F&docid=0JWo8mhfhhyXJM&tbnid=tRRLOg3TUDKizM&vet=12ahUKEwj g3c_dmciMAxXtQkEAHXPuL_YQM3oECHAQAA..i&w=600&h=452&hcb=2&ved= 2ahUKEwjg3c_dmciMAxXtQkEAHXPuL_YQM3oECHAQAA
13. Etchepare, R., & Hoek, J. P. (2021). Health risk assessment for the use of reclaimed water in urban environments: A review. Science of the Total Environment, 799, 149206. https://doi.org/10.1016/j.scitotenv.2021.149206
14. Garcia, M., & Islam, S. (2024). Evaluating residential rainwater harvesting systems in Tucson, Arizona. Journal of Water Resources Planning and Management, 150(2), 4021085.
15. Gov.in. (2020). Rain Water Harvesting. https://www.tn.gov.in/dtp/rainwater.htm
16. Gowda, H., & Kumar, N. (2025). RECYCLE AND REUSE OF GREYWATER TO AID.
17. Journal of Emerging Technologies and Innovative Research (JETIR), 12(2), 77–82.
18. Ibrahim, M., Yusuf, A., & Dung, E. J. (2023). Feasibility of Rainwater Harvesting in Jos, Plateau State: A Climatic Perspective. Journal of Water Resource and Environmental Engineering, 12(2), 45–53.
19. Joseph, A. E. (2022). Over 80% of Lagosians lack access to public water supply – Report – EnviroNews Nigeria. EnviroNews Nigeria. https://environewsnigeria.com/over-80- of-lagosians-lack-access-to-public-water-supply-report/?utm_source=chatgpt.com
20. Kobayashi, Y., Ashbolt, N. J., Davies, E. G. R., & Liu, Y. (2020). Life cycle assessment of decentralized greywater treatment systems with reuse at different scales in cold regions. Environment International, 134(November                            2019),                       https://doi.org/10.1016/j.envint.2019.105215
21. Kumar, R., Singh, R. D., & Sharma, K. D. (2022). Water resources of India. Current Science, 102(2), 152–163.
22. Landscape, H. L. &. (2025). 2025 Guide to Drought Resistant Landscaping – Horizon Lawn & https://horizonlawnkc.com/guide-to-drought-resistant- landscaping/?utm_source=chatgpt.com
23. Leong, J. Y. C., Oh, K. W., Poh, P. E., & Chong, M. N. (2019). A state-of-the-art review on grey water management: a survey from 2000 to Water Science and Technology,
24. 82(12), 2786–2799. https://doi.org/10.2166/wst.2020.463
25. Li, H., Wang, J., & Zhang, Y. (2023). Rainwater utilization and urban water management in Beijing. Journal of Hydrology, 598, 126159.
26. Li, Z., Boyle, A., & Reynolds, A. J. (2020). Life cycle assessment of decentralized greywater treatment systems with reuse at different scales in cold regions. Environment International, 134, 105215. https://doi.org/10.1016/j.envint.2019.105215
27. Madhuranthakam, C. M. R., AbuZaid, M., Chaalal, O., & Ghannam, T. (2023). Sustainable Water Management with Design and Economic Evaluation of Recycling Greywater at Abu Dhabi University—A Case Study on Decentralization. Sustainability, 15(23), 16208. https://doi.org/10.3390/su152316208
28. Mukhtar, (2024). WaterAid Launches Project to Improve Access to Sustainable Water Sanitation and Hygiene services in the Peri Urban area of Lagos State | WaterAid Nigeria. https://www.wateraid.org/ng/media/wateraid-launches-project-to-improve-access-to- sustainable-water-sanitation-and-hygiene?utm_source=chatgpt.com
29. Müller, , Mendel, G., & Winker, M. (2021). Integration of decentralized rainwater management strategies in urban areas: German experiences. Sustainability, 13(8), 4356.
30. Mwamila, T., Han, M., Ndomba, P., & Kim, T.-I. (2015). Tackling rainwater shortages during dry seasons using a socio-technical operational strategy. Water Science & Technology Water Supply, 15, 974–980. https://doi.org/10.2166/ws.2015.053
31. Ogbiye, S. A., Fagbenle, E., Busari, A. A., Onakunle, M., & Omole, D. O. (2021). Rainwater Harvesting: A Sustainable Alternative for Domestic Water Supply in South–Western Nigeria: A Case Study of Ado-Odo/Ota LGA, Ogun State. IOP Conference Series: Materials Science and Engineering, 1036(1), 12002. https://doi.org/10.1088/1757- 899X/1036/1/012002
32. Ogbozige, F. J. (2023a). Design of Rainwater Harvesting System: Basic Engineering and Economics. Malaysian Journal of Civil Engineering, 35(2), 1–11. https://doi.org/10.11113/mjce.v35.19439
33. Ogbozige, F. J. (2023b). Malaysian Journal Of Civil Engineering DESIGN OF RAINWATER HARVESTING SYSTEM : BASIC ENGINEERING AND ECONOMICS. 2, 1–11.
34. Olabode, O. F., & Comte, J.-C. (2024). Water scarcity in the fast-growing megacity of Lagos, Nigeria and opportunities for managed aquifer recharge. WIREs Water, 11(5), e1733. https://doi.org/https://doi.org/10.1002/wat2.1733
35. Olawale, , & Ibrahim, M. (2021). Policy Enforcement and Sustainable Water Practices in Lagos Mainland. African Journal of Environmental Policy, 9(4), 210–225.
36. Ren, X., Zhang, Y., & Chen, H. (2020). Graywater treatment technologies and reuse of reclaimed water for toilet flushing. Environmental Science and Pollution Research, 27(28), 34653–34663. https://doi.org/10.1007/s11356-019-05154-6
37. Sam. (2024). Drought-Resistant Landscaping: A How-To Guide – Ecomasteryproject. Ecomastery Project. https://www.ecomasteryproject.com/drought-resistant-landscaping- a-how-to-guide/?utm_source=chatgpt.com
38. Schrock, (n.d.). Water-Efficient Gardening and Landscaping. Mu Extension, University Of Missouri-Columbia, 1–6.
39. Seri. (2024). Education & Resources – Sonora Environmental Research Institute, Inc.
40. Silva, J. A., Santos, L. M., & Oliveira, R. P. (2023). Socio-economic impacts of rainwater harvesting in Brazil’s semi-arid regions. Journal of Arid Environments, 190, 104543.
41. socialpinpoint. (2020). Project overview. https://participate.melbourne.vic.gov.au/princes- park-stormwater-harvesting-project/project-overview
42. Udoh, S. E., & Nelson, I. I. (2023). Assessment of Rainwater Harvesting Systems for Sustainable Water Management in Ikot Osurua, Akwa Ibom State. Communication in Physical Sciences, 9(4). https://ajol.info/index.php/cps/article/view/291041
43. Zhang, A. (2025). Rainwater Harvesting System – Rainwater Harvesting System and The Rain Controller. Made-in-China.