The world is facing a water crisis of unprecedented scale, exacerbated by rising temperatures, erratic weather patterns, and increasing population pressure. According to the Intergovernmental Panel on Climate Change (IPCC), climate change is severely impacting global freshwater availability, with droughts, declining aquifer recharge, and deteriorating water quality becoming more frequent and intense. Already, 3.6 billion people experience water scarcity for at least one month each year, and this figure is projected to rise to over 5 billion by 2050 if urgent action is not taken.
At the heart of this crisis lies a fundamental need: securing reliable access to water in the face of climate uncertainty. For urban centres in Africa, home to some of the fastest-growing populations in the world, this challenge is particularly acute. Rapid urbanisation, coupled with outdated infrastructure and unequal water distribution, has made access to safe water increasingly precarious, especially in informal settlements and water-stressed neighbourhoods. As cities swell and rainfall becomes less predictable, one of the most practical, affordable, and climate-resilient solutions lies not in far-off reservoirs, but directly above our heads on rooftops.
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Rainwater harvesting is a simple but transformative practice that involves collecting rainwater from rooftops and storing it in tanks or cisterns for domestic or institutional use. Though the concept is ancient, it is gaining renewed attention globally as a cost-effective climate adaptation measure. According to a 2024 report by Climate Action, a flat roof of 100 square metres in an area with 600 mm of annual rainfall can capture up to 60,000 litres of water per year. Even in regions with as little as 200 mm of rainfall, such as parts of the Sahel, households can still harvest approximately 12,000 litres annually, enough to significantly reduce dependency on increasingly scarce groundwater or unreliable piped supplies.
Rainwater harvesting systems serve diverse functions, from flushing toilets and washing clothes to irrigating gardens and cleaning surfaces. In high-demand urban settings, such systems relieve pressure on public water infrastructure, cut household water costs, and reduce the volume and damage of stormwater runoff during heavy rains. In Switzerland, for example, the average precipitation of 1230 mm allows for the collection of up to 1000 litres per square metre of rooftop annually, offsetting thousands of litres in toilet and laundry water use.
Rooftop Harvesting Across African Cities
Across Africa, rooftop rainwater harvesting is being integrated into broader urban resilience strategies. In Kenya, the government and NGOs have actively promoted rooftop water catchment systems, particularly in rural and peri-urban areas of Nairobi, Kisumu, and Mombasa. Through public-private partnerships and donor-supported initiatives, schools and health clinics have been equipped with water storage tanks and guttering systems, enabling them to remain operational during dry spells and reducing the burden on already overstretched municipal supplies.
In Uganda, the Ministry of Water and Environment has included rainwater harvesting as a key component of the country’s National Climate Change Policy. Through the Uganda Rainwater Association, rain catchment systems have been installed in hundreds of rural households, with uptake increasing in urban areas like Kampala where piped water services are often unreliable. Additionally, some new residential estates are being encouraged to include rooftop collection systems in their building designs, especially in climate-vulnerable regions such as Karamoja and the Lake Victoria basin.
Nigeria is also seeing expanded use of rooftop harvesting, particularly in the cities of Lagos, Ibadan, and Abuja. With rapid urban growth and overstretched water infrastructure, state governments and civil society organisations have launched pilot schemes aimed at promoting rainwater harvesting as a practical solution for schools, hospitals, and small businesses. According to Climate Action, specific case studies in Nigeria have shown that hospitals and residences using tanks as small as 4–12 m³ were able to meet 70%–78% of their water needs. These findings have sparked interest in scaling up such systems as a standard feature in public buildings.
In Ethiopia, rooftop rainwater harvesting is being championed as part of the country’s Green Legacy Initiative and broader climate adaptation efforts. In Addis Ababa and secondary cities like Bahir Dar and Hawassa, local authorities have worked with development partners to provide incentives for installing water collection systems in schools and newly built housing units. With periodic droughts affecting water supply, rainwater systems have emerged as a low-tech, high-impact intervention to ensure continuity in water access, especially in education and health facilities.
Meanwhile, in South Africa, the post-2018 water crisis in Cape Town dramatically changed public attitudes towards water conservation. The city now promotes rooftop harvesting through building regulations, tax incentives, and public awareness campaigns. While South Africa has more developed infrastructure compared to many African nations, the Cape Town experience has become a cautionary tale and a model for how cities must prepare for future water stress.
Urban Climate Resilience Begins at the Rooftop
These national efforts reveal a growing consensus: rooftop rainwater harvesting is not just a rural solution or emergency fix, it is a viable strategy for climate adaptation in complex urban environments. From megacities like Lagos and Nairobi to smaller hubs such as Enugu and Mbale, the integration of rain harvesting systems is helping to decentralise water management and empower communities.
Beyond households and institutions, rainwater harvesting also plays a role in public health and education. In many schools and clinics, particularly in informal settlements or rural outskirts, harvested rainwater often provides the only reliable source of clean water for sanitation and hygiene. This has direct implications for disease prevention and dignity, especially for women and children.
Integrating Greywater and Urban Innovation
In tandem with rooftop harvesting, urban centres across Africa are also beginning to explore greywater recycling, reusing lightly used water from sinks, showers, and washing machines for non-potable purposes. Together, these systems create a decentralised water management model that builds resilience at the local level.
For instance, in South Africa, Cape Town’s experience during the 2018 Day Zero crisis sparked a wave of innovation in both household and municipal-level water conservation. Building codes are now being revised to incentivise the installation of rainwater tanks and greywater systems in new developments. In Kenya, developers in urban housing estates are incorporating rooftop catchment systems and smart irrigation controls as part of their sustainability offerings.
Australia provides a compelling global model. There, urban rainwater harvesting systems supply approximately 177 billion litres annually, 9% of residential water use valued at around $540 million. In rural areas, reliance on rainwater jumps to 63%, providing 109 billion litres. While the climatic and economic contexts differ, the model demonstrates what is possible with consistent investment, public policy support, and community buy-in.
A Framework for Climate Adaptation
Rainwater harvesting aligns with several global frameworks on climate resilience and sustainable development. The United Nations Framework Convention on Climate Change (UNFCCC) encourages nature-based solutions and community-led adaptation efforts. Under the Paris Agreement, countries are urged to implement locally appropriate solutions to enhance adaptive capacity and reduce vulnerability.
Moreover, Sustainable Development Goal 6 (Clean Water and Sanitation) and SDG 13 (Climate Action) both recognise the importance of ensuring universal access to safe and affordable water through sustainable means. Rooftop harvesting offers a scalable, low-carbon intervention that supports both objectives while also contributing to SDG 11 (Sustainable Cities and Communities).
In Africa, the African Union’s Agenda 2063 further reinforces the continent’s commitment to inclusive, environmentally sound development. Rooftop harvesting systems, especially when deployed in schools, health centres, and public buildings, embody the principle of “people-led solutions” embedded in that vision.
Investing in a Water-Secure Future
To unlock the full potential of rainwater harvesting in African cities, coordinated action is essential. Governments must incentivise the integration of harvesting systems in building codes and urban planning. Development finance institutions and climate funds can subsidise installation costs in low-income neighbourhoods. Meanwhile, community awareness campaigns are critical for changing public attitudes towards water conservation.
As climate change tightens its grip, Africa cannot afford to rely solely on centralised, infrastructure-heavy water delivery systems that are both capital-intensive and vulnerable to disruption. Rooftop rainwater harvesting offers an alternative, one that is decentralised, scalable, and grounded in the realities of urban life.
