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Water reuse and improving urban drainage, the great challenges of the future

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  • Water reuse and improving urban drainage, the great challenges of the future

About the blog

Jordi Agustí Vergés
Director of the Agencia Catalana del Agua between April 2013 and March 2019.
Schneider Electric
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We usually differentiate integrated water supply management systems into the portion that deals with raw water, and the portion that distributes treated water to the user, as the competent authority, the infrastructure, and sometimes the geographical scope of management, are different. But management should not be different between them: we should look for symmetries and ways where they complement each other.

In Catalonia, the management of the part of the supply system dealing with raw water and the part of the sanitation system from the main sewer to the treatment plant are under the responsibility of the Catalan Water Agency; it is linked to the management of the part of the supply system that distributes treated water to the user, and the part of the sanitation system that collects waste water from users, under the responsibility of municipal governments. If water availability and proper waste water treatment are guaranteed, the urban water cycle will be efficient and complete, both in quantity and quality.

The efficiency of the portion of the water supply network dealing with raw water in Catalonia is currently very high, about 95%. That per cent, a result of important efforts to optimise sustainable water resources, must be also reached in the municipal portion of the water supply network. Therefore, even though in most municipalities there are appropriate networks, constant improvements are required to avoid unnecessary losses.

Water reuse, one of the core areas of work

During 2018, the Catalan Water Agency and the Metropolitan Area of Barcelona materialised a commitment to using reclaimed water. An agreement between both entities — responsible for managing different portions of the urban water cycle, as described above — set the basis to promote water reuse in the area of Barcelona.

The first step, which has been active for almost one year, is using reclaimed water to protect the Llobregat delta aquifer from saline intrusion. This way, we preserve a strategic reserve for Barcelona and its metropolitan area during drought periods.

The Catalan Water Agency intends to promote, throughout this year, financial support to promote the use of reclaimed water by municipalities.

The decision to use reclaimed water goes even further. At the end of last November, a group of experts was set up, with 12 water professionals from different backgrounds, to analyse the possibility of increasing water availability in the final stretch of the Llobregat river by using reclaimed water. The idea is to expand the period of reuse, because right now the measure would only be implemented in case of a drought warning for the Metropolitan Region of Barcelona.

The Catalan Water Agency intends to promote, throughout this year, financial support to promote the use of reclaimed water by municipalities. Reusing water for garden irrigation, street flushing, and others, are solutions that will enable reusing a waste stream and, on the other hand, not having to use potable water for uses that do not require such quality. The work being done by regional authorities should have a counterpart at the local level, with a strong and determined commitment to a circular economy.

The challenge of sustainable drainage

When extreme weather phenomena take place, something that will occur more frequently in the coming years due to the effect of climate change, they reveal that current urban drainage systems often cannot absorb the volumes and flows generated. In this regard, we are aware of the problems caused by storm water in most Catalonian municipalities, especially in cities, and the problems they cause for sanitation systems, where grey water and clean water are combined and exceed the treatment capacity of infrastructure.

Technology, research and innovation offer increasingly more sustainable alternatives, which go beyond separate sewer networks, to improve urban drainage systems. In addition, they open up opportunities that involve different disciplines and can generate new professional profiles in architecture, urban design, landscaping, engineering, biology, energy efficiency, environmental consulting and urban planning, among others.

Synergies in the management of different portions of the water supply must seek the same objective, satisfying the demand in a sustainable manner

Sustainability applied to urban drainage systems will enable natural infiltration of storm water, reducing the volume and attenuating water input, thereby decreasing surface run-off during heavy rains.

Soil infiltration lightens the load on drainage and sanitation systems during heavy rains, at the same time as it helps rationalise investing in it, since it provides soils a moisture level similar to a natural regime, and benefits vegetation and green spaces in the city. This allows addressing the problem at its source, instead of transferring it downstream to sanitation systems or subsequent settlements.

Synergies in the management of different portions of the water supply must seek the same objective, satisfying the demand in a sustainable manner. And I mean, environmental, social, and economic sustainability.

 

 

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