#SWEM How the world uses rainwater: from green roofs to underground reservoirs

As part of the “Sustainable Weather Emergency Management (SWEM)” project, within the Interreg NEXT Romania-Ukraine 2021–2027 program, we aim to explore how different countries around the world are rethinking rainwater. In many modern cities, rainwater is no longer perceived as a by-product but rather as an additional resource capable of reducing pressure on water supply systems and helping cities cope during periods of extreme heat.

In Asia - from Tokyo to Singapore - water runoff from rooftops and paved surfaces is directed into large underground reservoirs. From there, it is used for firefighting, cooling technical systems, building maintenance, and irrigating urban gardens. This approach not only conserves drinking water but also reduces the risk of flooding during heavy rainfall, as a portion of precipitation does not immediately enter the sewer system.

In Europe, rainwater is increasingly being utilized in residential areas and public spaces. It supports green infrastructure — from parks to sports facilities. Green roofs and permeable surfaces enable cities to better retain and store precipitation, thereby mitigating heat impacts and providing additional moisture for vegetation. Such solutions demonstrate that rainwater can become an important element of urban resilience. By using it wisely, cities become less dependent on centralized systems and better prepared for climate change.

This publication has been produced with the financial support of the European Union. Its contents are the sole responsibility of the Executive Committee of the Ivano-Frankivsk City Council and do not necessarily reflect the official position of the European Union or the management structures of the Interreg NEXT Romania-Ukraine 2021-2027 Program.