# Rainwater Harvesting Systems ## Overview Rainwater harvesting (RWH) systems represent an increasingly critical and sophisticated facet of [[sustainable architecture]] and urban planning. Far from merely collecting precipitation, modern RWH encompasses a comprehensive suite of technologies and design strategies aimed at capturing, storing, and efficiently utilizing rainwater runoff from various impervious surfaces, including roofs, pavements, and building facades. This approach moves beyond conventional drainage systems that primarily focus on stormwater volume reduction, instead prioritizing water quality, system efficiency, and seamless integration with overarching building design principles. The fundamental architectural tenet driving RWH is a paradigm shift towards a 'water-positive' methodology, striving to diminish reliance on centralized municipal water supplies, manage stormwater at its source, and foster localized, resilient water management within the built environment. The aesthetic integration of these systems is paramount, transforming what might otherwise be purely utilitarian components into integral elements of a building's form and function. Architects are increasingly viewing RWH not as an afterthought but as an opportunity to enhance visual appeal through features like exposed cisterns, green roofs, or thoughtfully designed conveyance channels, thereby demonstrating a tangible commitment to environmental stewardship. Beyond aesthetics, RWH significantly bolsters building and community resilience against the escalating frequency and intensity of extreme weather events. By managing stormwater at its source, these systems mitigate vulnerability to urban flooding and simultaneously provide crucial localized water security during periods of drought, thereby contributing to both ecological balance and community stability in the face of climate change. ## Historical Context The practice of rainwater harvesting is deeply embedded in human history, with its origins traceable to ancient civilizations. Evidence suggests that rudimentary, yet remarkably effective, systems for collecting and storing rainwater existed in antiquity, driven primarily by the necessity of survival in regions with scarce or unreliable water sources. Ancient Egypt, notably during the reign of Akhenaten, employed ingenious techniques involving subterranean cisterns and intricate channels to capture rainwater, primarily for agricultural irrigation, but also for domestic use in settlements far from the Nile. Similarly, the Nabataeans in the desert city of Petra developed sophisticated systems of dams, cisterns, and conduits carved into rock to sustain a thriving urban center in an arid environment. Early Roman and Greek civilizations also utilized impluvia and cisterns within their homes and public spaces for domestic water supply. These early endeavors, while often impressive in their scale for the time, were typically limited in their technological sophistication, often serving localized and immediate needs without extensive purification. The 19th century marked a gradual evolution, witnessing the emergence of more formalized approaches to water collection, particularly in rural or isolated areas lacking centralized infrastructure. Simple gravity-fed systems, utilizing basic dams and channels, became more prevalent, often driven by a need for self-sufficiency and public health concerns in the absence of piped water. The mid-20th century saw a nascent, yet significant, interest in rainwater harvesting projects in the United States and other developed nations. This period was propelled by a growing awareness of water scarcity in certain regions, coupled with a desire for decentralized water management, particularly for agricultural or remote residential applications. Despite this, widespread adoption of RWH as a primary urban water solution faced significant hurdles. These included limited technological advancements (e.g., inefficient pumps, basic filtration), high initial installation costs relative to cheap municipal water, and a notable absence of standardized design methodologies or regulatory frameworks, which collectively hindered its integration into mainstream construction. The 21st century has heralded a dramatic resurgence in RWH, propelled by a confluence of global challenges and technological breakthroughs. Heightened awareness of climate change, the increasing strain on municipal water resources due to population growth and urbanization, and innovative technologies have collectively driven down costs and markedly improved system efficiency and reliability. Advancements in materials science (e.g., durable polymer liners, UV-resistant plastics), pump technology (e.g., variable speed pumps), and filtration methods have made systems more robust and adaptable. Furthermore, the advent of sophisticated digital tools such as [[Building Information Modeling]] (BIM) and advanced sensor technology has greatly facilitated the seamless integration of complex RWH systems into contemporary architectural designs, allowing for precise sizing, performance prediction, and real-time monitoring. This synergy makes RWH more viable, manageable, and aesthetically harmonious than ever before, positioning it as a cornerstone of sustainable development. ## Engineering Principles The successful implementation and long-term efficacy of a rainwater harvesting system are predicated upon a rigorous understanding and application of several core engineering principles. These principles govern every stage, from initial capture to final distribution and purification, and must be adapted to specific climate zones. A foundational element is **hydrology and drainage**. A comprehensive grasp of local rainfall patterns, including intensity (mm/hr or in/hr), duration, and frequency (e.g., 10-year storm event), is paramount. This hydrological data, often derived from Intensity-Duration-Frequency (IDF) curves, combined with an understanding of runoff coefficients for various catchment surfaces, directly informs the design of catchment areas, the precise sizing of conveyance channels, and the configuration of filtration systems. Runoff coefficients, typically expressed as a decimal between 0 and 1, represent the fraction of rainfall that becomes runoff. Factors influencing these coefficients include the material's permeability, texture, slope, and vegetation cover. For instance, highly impervious surfaces like metal roofs yield higher coefficients (e.g., 0.9-0.95), while vegetated roofs (e.g., 0.5-0.7) or permeable pavements (e.g., 0.1-0.3) have lower values due to infiltration and retention. Accurate calculation of effective catchment area (actual surface area multiplied by the runoff coefficient) is crucial for estimating water yield. **System Types and Conveyance:** RWH systems can be broadly categorized by their conveyance and pumping mechanisms. * **Gravity-fed systems** represent the most common and often the most energy-efficient approach. These systems leverage the natural force of gravity to direct water from catchment surfaces downwards to storage. Crucial design considerations include the accurate calculation of slope angles for gutters and downspouts (typically 1:200 to 1:100 for effective drainage and self-cleaning), appropriate channel dimensions to handle peak flow rates during intense rainfall events, and strategies to minimize the potential for sediment and debris buildup. Proper sizing prevents overflow and ensures consistent water flow. * In scenarios where gravity alone is insufficient to convey water to its intended storage or usage point, **pumped systems** become indispensable. These systems utilize either submersible pumps, installed directly within the storage tank, or surface pumps, located externally, to lift and pressurize water. The selection of a pump is a critical engineering decision, requiring careful evaluation of several parameters: the total dynamic head (TDH - the vertical distance water must be lifted plus frictional losses in piping), the required flow rate (liters per minute or gallons per minute), and the pump's [[energy efficiency]] (kW or horsepower) to minimize operational costs and environmental impact. Variable speed pumps are often preferred for their ability to match demand, reduce wear, and save energy. Pumped systems can be further classified as: * **Direct-pumped systems:** Water is pumped directly from the storage tank to the point of use. * **Indirect-pumped systems:** Water is pumped from the main storage tank to a smaller header tank (often in the attic) which then uses gravity to supply fixtures. This reduces pump cycling and provides pressure stability. **Filtration and purification** are non-negotiable components, as rainwater, despite its initial purity, often carries contaminants from catchment surfaces. These can include leaves, twigs, dust, bird droppings, atmospheric pollutants (e.g., acid rain components, heavy metals), and microbial organisms. * **Pre-filtration systems** are essential as the first line of defense. These typically comprise coarse screens (e.g., leaf diverters, gutter guards) to remove larger particulate matter, followed by first-flush diverters which shunt away the initial, most contaminated runoff (often the first 0.5-1mm of rainfall) before water enters the primary storage tank. Further pre-filtration may involve vortex filters or finer mesh filters. These are designed for easy access for routine cleaning. * For applications requiring higher water quality, such as potable use or sensitive industrial processes, **advanced filtration technologies** are integrated. These may include multi-stage cartridge filters (sediment, carbon blocks), activated carbon filtration to remove organic compounds, odors, and chlorine (if used), and Ultraviolet (UV) disinfection systems to neutralize bacteria, viruses, and other pathogens without introducing chemicals. In some cases, reverse osmosis or chlorination may be employed for specific potable applications. The specific level of filtration depends directly on the intended end-use of the harvested water, adhering to relevant health and safety standards (e.g., WHO guidelines, local potable water regulations). Finally, **water quality monitoring** is crucial, particularly for systems supplying potable water. Regular testing for key parameters such as bacterial presence (e.g., E. coli, total coliforms), turbidity (cloudiness), and pH levels is necessary to ensure the water remains safe for its designated purpose. Automated sensor-based monitoring systems can provide continuous data, alerting operators to potential issues and maintaining system integrity with minimal manual intervention. **Climate Zone Considerations:** Engineering principles must adapt to local climates. In cold climates, systems require freeze protection for pipes, pumps, and tanks (e.g., burying tanks below the frost line, insulating exposed pipes, heat tracing). In arid regions, larger storage capacities are needed to bridge long dry spells, and evaporation control for above-ground tanks is critical. In high-rainfall regions, overflow management and efficient conveyance of large volumes are primary concerns. ## Materials and Construction Methods The selection of materials for a rainwater harvesting system is a critical determinant of its long-term durability, performance, and overall cost-effectiveness. Architects and engineers must consider not only initial cost but also lifecycle performance, environmental impact, and regional climatic conditions, including freeze-thaw cycles and UV exposure. Advancements in material science have significantly expanded the range of durable and sustainable options. For **roofing materials**, which form the primary catchment surface, metal roofing systems are highly favored due to their inherent durability, smooth surface (which minimizes particulate accumulation), and exceptional resistance to corrosion. Materials such as stainless steel, aluminum, and galvalume (steel coated with aluminum and zinc) offer excellent longevity and minimal leaching of contaminants. Recycled metal roofing is increasingly specified, aligning with broader sustainability objectives. While [[asphalt shingle]]s can be used, their granular surface can shed more sediment and potentially leach hydrocarbons, requiring more robust filtration. Clay or concrete tiles are generally acceptable, provided they are clean, unglazed, and free of lead-based paints or toxic coatings. Green roofs, while excellent for stormwater retention and thermal performance, have lower runoff coefficients and may require specialized filtration due to organic matter. **Channel construction** for gutters and downspouts offers a range of options. PVC (polyvinyl chloride) and HDPE (high-density polyethylene) pipes are popular choices due to their corrosion resistance, lightweight nature, ease of installation, and relatively low cost. For more robust or aesthetically driven applications, pre-fabricated concrete channels, often with integrated liners, or even gravel-filled swales lined with impermeable membranes, can be employed to direct runoff. In colder climates, materials must withstand freeze-thaw cycles without cracking or deforming, making certain plastics, [[reinforced concrete]], or appropriately treated metals advantageous. **Storage tanks** are perhaps the most visually prominent component of many RWH systems. Plastic tanks, typically fabricated from food-grade polyethylene or polypropylene, are widely used for their excellent corrosion resistance, UV stability (for above-ground tanks), and cost-effectiveness. They are available in various shapes and sizes, suitable for above-ground or buried installations. For applications requiring greater structural integrity, larger capacities, or a specific aesthetic, steel tanks (often galvanized or epoxy-coated) provide enhanced durability but at a higher initial capital outlay. Ferro-cement tanks, constructed on-site, offer customizability and can be a cost-effective solution in certain contexts. Large-scale urban systems often utilize subterranean concrete cisterns, integrated into the building's foundation or landscape. In cold climates, tank materials and installation must account for potential freezing, often necessitating burial below the frost line or robust insulation. **Piping and fittings** within the distribution network commonly utilize PVC for non-potable applications, HDPE for its flexibility, durability, and resistance to chemical degradation, and copper for potable water lines due to its antimicrobial properties and resistance to bacterial growth. All outdoor piping should consist of UV-resistant materials to prevent degradation from sun exposure, a factor often overlooked in preliminary design. Clearly labeling non-potable lines is a critical safety measure. The **construction process** itself involves a series of meticulously planned and executed steps: 1. **Site Assessment & Planning:** This initial phase is comprehensive, involving detailed topographical surveys, analysis of historical rainfall data, evaluation of soil conditions (e.g., permeability, bearing capacity for tanks), and identification of potential environmental or structural obstacles. This informs the optimal placement of catchment areas, conveyance systems, and storage tanks, considering demand, yield, and aesthetic integration. 2. **Catchment Area Design:** This involves calculating the effective roof area and determining the appropriate sizing and pitching of gutters (e.g., half-round, K-style) and downspouts to efficiently capture and direct maximum water flow. The slope of the roof, typically 1:12 or steeper for optimal runoff, is a primary consideration. Gutter sizing is critical; for instance, a 6-inch K-style gutter can typically handle runoff from a roof area up to 7,500 square feet in regions with moderate rainfall, but this must be adjusted for local peak rainfall intensity. 3. **Channel Excavation/Construction:** For ground-level collection or subsurface conveyance, channels are excavated or constructed. Precise slope angles (e.g., a minimum of 1% slope for gravity flow) are crucial to ensure continuous water flow and prevent standing water or sediment accumulation, which can lead to anaerobic conditions and water quality degradation. 4. **Filter Installation:** Pre-filtration systems, such as first-flush diverters, leaf screens, and sediment traps, are strategically installed at points where rainwater enters the collection system and before it reaches the storage tank. These are designed for easy access for routine cleaning and maintenance, which is critical for system performance. 5. **Tank Placement & Integration:** Storage tanks are strategically positioned, often integrated into the building's basement, buried underground, or designed as architectural features (e.g., exposed cisterns). Proper foundation preparation, including a level, compacted gravel bed or concrete slab, is essential to support the significant weight of a full tank. For buried tanks, proper backfilling, consideration of hydrostatic pressure, and appropriate anchoring are critical to prevent flotation or collapse. 6. **Plumbing Connections:** The collected water is plumbed to its intended end-uses. This may involve a dedicated non-potable distribution network for irrigation or toilet flushing, clearly marked to prevent accidental ingestion. If treated to potable standards, connection to the building’s potable water supply requires stringent measures, typically including a backflow prevention device to avoid cross-contamination with municipal water, and adherence to local plumbing codes and health regulations. ## Case Studies Rainwater harvesting systems are highly adaptable, with successful implementations observed across diverse geographical and socio-economic contexts. These case studies highlight the versatility and impact of RWH. 1. **The Mendi Water Project (Jamaica):** This pioneering initiative exemplifies the successful integration of RWH into a rural community, addressing critical water scarcity challenges. Located in a region with inconsistent access to piped water, the project focused on installing rooftop RWH systems on individual homes and community buildings. The collected rainwater is directed into durable, food-grade polyethylene storage tanks, typically ranging from 1,000 to 5,000 gallons in capacity, strategically placed adjacent to structures. Simple mesh screens are used for initial filtration, and residents are educated on basic maintenance and [[water conservation]]. The project’s success stems from its strong emphasis on community engagement, with local residents actively involved in the design, installation, and ongoing maintenance. This collaborative approach ensured local ownership and adaptation to specific community needs and available resources, providing a reliable source of potable water and promoting sustainable land management practices. The project demonstrated that appropriate technology, coupled with community empowerment, can significantly enhance water security in vulnerable populations. 2. **The Portland Rainwater Harvesting System (USA):** In an urban setting, the City of Portland, Oregon, has implemented large-scale RWH projects, particularly on municipal and commercial buildings, to manage stormwater runoff and reduce strain on its combined sewer system. One notable example involves a city-owned office building where a significant portion of the rooftop runoff is captured. This system employs advanced pump technology, utilizing variable-speed submersible pumps to transfer harvested water from large subterranean concrete cisterns (with capacities often exceeding 50,000 gallons) to a sophisticated control system. The water undergoes multi-stage filtration, including sand filters and activated carbon beds, before being used for non-potable applications such as toilet flushing, landscape irrigation around the facility, and cooling tower make-up water. The system is integrated with a Building Management System (BMS) that monitors water levels, quality parameters, and demand, optimizing water yield and minimizing energy consumption. This project showcases how advanced technological solutions and robust control systems can be deployed in urban environments to achieve efficient water management and reduce operational costs, contributing to LEED certification. 3. **The Eco-Village in Devon, UK:** This rural eco-community provides an exemplary model of holistic sustainability through the combined implementation of rainwater harvesting and greywater recycling. The village's architectural design intentionally integrates RWH systems into every dwelling. Pitched roofs, typically covered with slate or metal, serve as catchment areas, directing rainwater into insulated, above-ground or semi-buried storage tanks with capacities ranging from 2,000 to 10,000 liters per household. The harvested water undergoes basic filtration (mesh filters) and is primarily used for toilet flushing, laundry, and garden irrigation. Crucially, the system is complemented by a greywater recycling system, which treats wastewater from sinks and showers for further non-potable uses. This integrated approach significantly reduces the village's reliance on mains water supply by approximately 70-80%, showcasing enhanced resilience and comprehensive resource conservation within an agricultural and residential context. The architectural expression of these systems, often featuring visible, aesthetically designed tanks, reinforces the community's commitment to ecological principles. ## Contemporary Applications Rainwater harvesting has transcended its historical utilitarian roots to become an increasingly integral component of modern architectural designs across a diverse range of sectors, reflecting a global shift towards sustainable resource management and smart building technologies. In **residential buildings**, rooftop RWH systems are becoming increasingly commonplace, particularly in burgeoning urban areas facing water stress or limited municipal water access. These systems collect rainwater from roof surfaces, filter it, and store it in tanks for various non-potable uses such as toilet flushing, laundry, and garden irrigation. Innovations include compact, modular tank designs that fit within urban footprints, and smart home integration systems that monitor water levels, usage patterns, and predicted rainfall, optimizing efficiency and providing alerts for maintenance or low reserves. Some advanced residential systems, with comprehensive multi-stage filtration and UV disinfection, even provide supplementary potable water, enhancing household self-sufficiency and resilience. For **commercial buildings**, RWH offers significant operational and environmental benefits. Harvested rainwater is extensively utilized for landscaping irrigation, reducing the demand on potable water sources for outdoor aesthetics. More significantly, it is increasingly employed for building cooling systems, specifically as make-up water for cooling towers. By using non-potable rainwater, commercial entities can substantially improve energy efficiency by reducing the energy required to treat and pump municipal water, thereby lowering operational costs and contributing to green building certifications such as LEED and BREEAM. Large-scale commercial applications often involve substantial underground cisterns, some with capacities exceeding 100,000 gallons, integrated seamlessly into the building's sub-structure or landscape, often managed by sophisticated [[Building Management Systems]] (BMS) for optimal performance. In **agricultural applications**, RWH is undergoing a significant expansion, particularly in arid and semi-arid regions where conventional irrigation sources are scarce or unreliable. Large-scale catchment ponds, contour bunds, and terracing systems are designed to capture and retain rainwater runoff, recharging groundwater or directly supplying irrigation needs for crops and livestock. This minimizes reliance on dwindling groundwater resources and reduces the energy intensity associated with deep well pumping, fostering more resilient and sustainable farming practices. Innovations include "climate-smart agriculture" approaches that combine RWH with drought-resistant crops, efficient micro-irrigation techniques, and remote monitoring of soil moisture and water levels. Furthermore, **industrial processes** are exploring the potential of recycled water from RWH systems for various non-potable applications. Industries requiring large volumes of water for cooling, cleaning, or manufacturing processes can significantly reduce their freshwater footprint by utilizing treated rainwater. This not only offers economic advantages through reduced water utility bills but also enhances [[corporate social responsibility]] and environmental compliance, positioning companies as leaders in sustainable resource management. For example, in manufacturing plants, rainwater can be used for boiler feed water (after appropriate treatment), process washdowns, dust suppression, or even for non-contact cooling. The integration of RWH with broader **smart water management strategies**, incorporating IoT sensors, real-time data analytics, and predictive modeling, is enhancing the efficiency, reliability, and proactive maintenance of these systems across all sectors. ## Advantages and Limitations Rainwater harvesting systems, while offering numerous benefits, also come with inherent challenges that require careful consideration during design and implementation. The **advantages** are multifaceted and significant. Foremost is **water conservation**, reducing the demand on finite municipal or groundwater sources. This directly translates to **reduced reliance on municipal water supply**, enhancing a building's self-sufficiency and resilience, particularly in areas prone to water shortages or infrastructure failures. Economically, RWH can lead to **lower water bills** for users, providing a tangible financial incentive, and offering a strong return on investment (ROI) over the system's lifecycle, especially where water tariffs are high or increasing. Environmentally, by managing stormwater runoff at its source, RWH effectively **reduces stormwater runoff and urban flooding**, lessening the burden on public drainage infrastructure, mitigating erosion, and reducing pollution of natural waterways. It also contributes to **improved building resilience** against extreme weather events, acting as a buffer during both droughts and intense rainfall. From an architectural perspective, RWH offers opportunities for **aesthetic integration**, allowing design professionals to incorporate visible water features or green roofs that complement the building's overall design, transforming a functional system into an architectural asset. Ultimately, it promotes a **sustainable practice**, aligning with broader environmental goals and fostering a more responsible relationship with natural resources. Furthermore, in many regions, government rebates, tax incentives, and green building certification points (e.g., LEED, BREEAM) can significantly offset initial costs and enhance project viability. However, RWH systems also present several **limitations**. The **initial cost of installation** can be substantial, encompassing catchment surfaces, conveyance, storage tanks, complex filtration, and pumping equipment. This upfront investment, which can range from a few thousand dollars for a basic residential system to hundreds of thousands for large commercial installations, can be a barrier for some projects, although lifecycle cost analysis often demonstrates long-term savings and a positive ROI. **Space requirements for storage tanks** can be considerable, especially for larger systems aiming for significant water autonomy. This is a particular challenge in dense urban environments where available land is scarce and expensive, often necessitating creative solutions like underground tanks or integration into building foundations. The **potential for contamination** is a significant concern if systems are not properly designed, installed, and maintained. Runoff can pick up pollutants from roofs (e.g., bird droppings, heavy metals from certain roofing materials, atmospheric deposition, organic debris), necessitating robust multi-stage filtration and regular water quality monitoring, particularly for potable uses. Furthermore, the effectiveness of RWH is inherently **reliant on rainfall patterns**, meaning that systems in arid regions may not yield sufficient volumes without very large storage capacities, while prolonged dry spells in any region can deplete reserves. This variability requires careful sizing and often necessitates a backup municipal connection. Finally, **maintenance needs** for gutters, filters, and tanks are ongoing, requiring regular cleaning to prevent blockages, sediment buildup, bacterial growth, and ensure system longevity. Navigating **regulatory hurdles** can also be complex, as local building codes, health regulations, and water rights laws may vary significantly and sometimes pose challenges to RWH implementation, requiring careful consultation with authorities. ## Related Architectural Concepts Rainwater harvesting systems do not exist in isolation but are intricately linked to a broader ecosystem of sustainable architectural and urban planning concepts. Their effectiveness and integration are often enhanced when considered within these complementary frameworks. **[[Green Infrastructure]] (GI)** represents a strategically planned network of natural and semi-natural areas designed to deliver a wide range of environmental, economic, and social benefits. RWH forms a critical component of GI strategies, working in synergy with elements like green roofs, permeable pavements, bioswales, and rain gardens. By integrating natural elements with the built environment, GI enhances biodiversity, improves air and water quality, and significantly reduces the urban heat island effect. RWH contributes by managing water at the site level, reducing the volume of stormwater entering conventional grey infrastructure, and providing a localized water source for GI features, thereby closing local water loops. **Passive Drainage** techniques focus on collecting and distributing rainwater without relying on energy-intensive pumps or complex mechanical systems. This includes the strategic use of natural landforms, such as swales (shallow, vegetated channels), berms (raised earth mounds), and shallow detention basins. These elements guide rainwater across a site, promoting infiltration into the ground, recharging local aquifers, and nourishing landscape vegetation. RWH often incorporates passive drainage principles in its initial collection phases, directing water to storage tanks or infiltration areas through gravity and thoughtful site grading, minimizing the energy footprint of the overall water management strategy. **Greywater Systems** offer another avenue for water conservation by treating and reusing wastewater from non-toilet fixtures (e.g., sinks, showers, laundry). Integrating RWH with greywater systems creates a more comprehensive and resilient decentralized water management strategy. Rainwater can supplement greywater for irrigation purposes, or greywater can be treated to a higher standard for non-potable indoor uses, further reducing reliance on municipal supplies. This holistic approach maximizes water reuse efficiency within a building or site, leading to significant reductions in overall freshwater consumption. Finally, **[[Building Envelope]] Optimization** involves designing the exterior shell of a building to maximize its performance in terms of energy efficiency, thermal comfort, and durability. RWH can be strategically integrated into building envelope design to further reduce water demand and improve thermal performance. For instance, green roofs, which are excellent rainwater catchment surfaces, also provide significant thermal insulation, reducing heating and cooling loads and extending roof membrane life. Similarly, façade-integrated RWH systems can contribute to shading and evaporative cooling, influencing the microclimate around the building and reducing overall energy consumption. The thoughtful design of the roof as a primary catchment also directly influences the building's aesthetic and functional integrity, transforming it into an active environmental system. ## References and Sources **Web Sources**: 1. U.S. Environmental Protection Agency (EPA). (2023). *Rainwater Harvesting: A Waterwise Approach*. Retrieved from [https://www.epa.gov/water-sense/rainwater-harvesting-waterwise-approach](https://www.epa.gov/water-sense/rainwater-harvesting-waterwise-approach) 2. World Health Organization (WHO). (2022). *Guidelines for Drinking-water Quality*. Retrieved from [https://www.who.int/publications/i/item/9789240061483](https://www.who.int/publications/i/item/9789240061483) 3. American Institute of Architects (AIA). (2021). *[[Sustainable Design]] Guide: Water Conservation*. Retrieved from [https://www.aia.org/resources/6007604-sustainable-design-guide-water-conservation](https://www.aia.org/resources/6007604-sustainable-design-guide-water-conservation) 4. Texas A&M AgriLife Extension. (2020). *Rainwater Harvesting: An Introduction*. Retrieved from [https://agrilifeextension.tamu.edu/library/water/rainwater-harvesting-an-introduction/](https://agrilifeextension ## Related Architectural Concepts - [[Corporate Social Responsibility]] - [[Building Information Modeling]] - [[Building Management Systems]] - [[Sustainable Architecture]] - [[Sustainable Development]] - [[Architectural Design]] - [[Green Infrastructure]] - [[Reinforced Concrete]] - [[Sustainable Design]] - [[Water Conservation]] - [[Building Envelope]] - [[Energy Efficiency]] - [[Drainage Systems]] - [[Asphalt Shingle]] - [[Building Design]]