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Real-scale demonstration project for improving the integrated management of urban drainage and reducing the impact of untreated rainwater on natural aquatic systems. The pilot cities are Barcelona and Berlin.

The function of the urban draining system and sewers is to collect urban waste water, rainwater and surface runoff. When the system is of a unity type, it transports such water along the same pipes. Once the water reaches the treatment plants, it is treated for the purposes of removing its solids in suspension and pollution loads and then returned to the natural environment (river spaces, lakes and coastal areas).
Sustainable management of this water helps to close the anthropogenic water cycle, ensure public health and reduce the pollutant load that reaches the environment. Of course, during episodes of intense or prolonged rain, the volume of water may exceed the capacity of the sewerage system or treatment plants and untreated rainwater may be directly discharged to the environment.

Such discharges have a negative effect on aquatic ecosystems, as the pollution that reaches them affects their physico-chemical and microbiological quality. Environment degradation may also have an impact on human health, seeing as beaches and river beds are leisure spaces.
Big cities such as Barcelona and Berlin – the two taking part in the project – have integrated urban-drainage management systems which enables them to anticipate risks and offer maximum health guarantees.


One of the United Nations’ Sustainable Development Goals (SDGs), launched in 2015 under the New World Agenda, is to ‘ensure the availability of water and its sustainable management and drainage for all’ (Goal No. 6), counting on the active participation of local communities in improving management.

This goal, however, is not in isolation from the others (17 in all), but needs to be assessed in a cross-cutting way so as to build a narrative that integrates all perspectives: environmental, social, economic and public health.