Roofs, rain and life: Rainwater harvesting for safe water supply and sustainable co-benefits


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Rainwater Harvesting Tank in Rwanda. Photo Credit: C. Rieck (2011)/Sustainable Sanitation Alliance (SuSanA) Secretariat
Rainwater Harvesting Tank in Rwanda. Photo Credit: C. Rieck (2011)/Sustainable Sanitation Alliance (SuSanA) Secretariat

Co-author: Carmen Anthonj , Assistant Professor GeoHealth, Geo-Information Science and Earth Observation (ITC) of the University of Twente


Key Takeaways

  • Rainwater harvesting is a valuable part of a water management strategy, can contribute to household water security and should be encouraged and facilitated by governments.
  • Governments can create an enabling environment and policy framework that regulates and incentivizes the implementation of RWH systems. 
  • Governments can promote and support RWH by raising public awareness and develop an appreciation for water resources among residents. 

In an era of the COVID-19 pandemic, the Water Supply, Sanitation and Hygiene (WASH) sector is gaining much more (deserved) attention due to its importance in containing and mitigating the spread of the deadly virus. Moreover, many countries have even established constitutional mandates recognizing WASH services as a Human Right of the population after the United Nations adopted such resolution in 2010.  But despite the importance and recognition of the WASH sector globally in the current era, many developing countries are still far away from reaching the Sustainable Development Goals (SDGs) for Water and Sanitation. Accelerated and sustained coverage of WASH services for all have been the source of debate over the last decade, particularly because of the difficulty of bringing these services to rural and dispersed populations in cost-effective ways and under tight fiscal constraints. 

Accelerating, sustaining and universalizing WASH must rely on multiple options that can be scaled up at reasonable costs to the government, the providers of maintenance and, ultimately, users.  One of the many potential solutions that deserve attention and could help meet these ambitious objectives are rain harvesting solutions. There have been some interesting field case studies in Tanzania that illustrate how rainwater harvesting (RWH) solutions produce spillover benefits on agriculture while increasing resilience. Such effects have been observed even in dry areas in Pakistan. Also, many advocates show RWH breaks the monopolistic (and in many occasions unsustainable) structure of the usual utility service providers. The debate of whether RWH is a viable option within the menu of solutions available to accelerate, sustain (both environmentally and economically) and universalize access to safe water is still open. Because of that reason, this short literature review can provide a clearer “picture” of the features and characteristics of these options.  

RWH is useful for the accumulation and deposition of rainwater in specially prepared collection and catchment areas, such as roofs, or areas on the ground, and has numerous (unquantified) benefits. In water-rich countries like Malaysia or Colombia, for instance, RWH has proven useful in improving water security at household and personal scales, and with financial viability. Rainwater can act as a buffer against shortfall, as an alternative primary source in rural areas that lack conventional water supply systems, and as a backup supply source in urban areas. A cost-benefit analysis of RWH options pointed out that these options are not economically viable, but without quantifying the multi-purpose benefits of RWH. For instance, RWH systems can mitigate service interruptions from centralized water distribution systems, or overuse of water from wells in arid regions. RWH can also be used to store rainwater for emergencies such as earthquakes, and as an adaptation strategy to cope with climate extremes such as droughts.  In addition, RWH can help reduce the impacts of flooding through the reallocation of water in small watersheds dedicated for agro-forestry and reduced urban runoff.  

If well managed, rainwater quality can be safe in combination with a framework of international standards. Rainwater is considered an ‘improved water source,’ according to the WHO & UNICEF Joint Monitoring Programme (WHO & UNICEF, 2019), when these parameters and standards are met. Therefore, investments in upscaling RWH count towards meeting the targets agreed by national governments for WASH as part of the SDG 6.  

AMALI, Amali Abraham
September 16, 2021

A very interesting article on RWH. Studies are increasing to show the viability of the system as an alternative water supply. Thanks to WHO & UNICEF for recognising it as an "improved water source". This would go a long way in increasing access in addition to the multiple and already proven rural and urban benefits.

But before rushing into the issues of scale, for a small watershed, harvesting a considerable amount of rainwater could be detrimental to downstream ecosystems. In this regard, we could be careful to first quantify thresholds beyond which this tipping points exists. In other words, how much water can be harvested without grossly affecting the watershed especially in arid regions.