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Reclaimed water reuse: dealing with water scarcity in Spain

The problem of drought in Catalonia and Andalusia is not an isolated phenomenon, but an increasingly frequent and harsh reality in Spain due to climate change. The country, characterized by a Mediterranean climate, faces prolonged periods of low rainfall, with a direct impact on the availability of water resources for human consumption, agriculture and industry.

In this context, and with the permission of desalination, water reuse emerges as a strategic response to this problem, offering the possibility of putting treated wastewater back into the water cycle.

Water reuse emerges as a strategic response to take advantage of treated wastewater putting it back into the water cycle

Water reuse in Spain

Spain is the second country in the European Union that reuses the most water, positioning itself as one of the leaders in the implementation of water reuse technologies, especially concerning wastewater treatment and reclamation. The regulatory framework in Spain, initially established by Royal Decree 1620/2007, which establishes the legal regime for the reuse of treated water, placed Spain in a pioneering position in this field, and has provided a solid basis for the development of infrastructure and technologies for water reuse.

In addition, following European guidelines, which consider water reuse crucial to guarantee an additional source of safe water, as well as to reduce the pressure of climate change, at the national level Spain has a Spanish Circular Economy Strategy (EEEC). This includes a line of action focused on water reuse and purification, with the aim of "promoting an efficient use of water resources that makes it possible to reconcile the protection of the quality and quantity of water bodies with its sustainable and innovative use". Spain has more than 2,000 WWTPs, and according to data from the XVII National Study of Drinking Water Supply and Sanitation in Spain 2022 by AEAS-AGA, 343 hm³ of treated and reclaimed water was reused in Spain, confirming a stable upward trend in recent years, led by Murcia, Valencia and Andalusia, followed by the Balearic Islands, Catalonia, Madrid and the Canary Islands.

  • Spain is the second country in the European Union that reuses its water the most

Also worth noting is the National Plan for Wastewater Treatment, Sanitation, Efficiency, Savings and Reuse (DSEAR Plan), which has a governance objective focused on promoting the reuse of wastewater. This framework has been complemented by local and regional policies that promote circular economy practices, focusing on urban wastewater treatment and reuse as a key strategy for water sustainability.

Taken together, this approach not only relieves pressure on natural water resources, but also promotes more sustainable water use.

Examples of the use of reclaimed water in Spain

The use of reclaimed wastewater as a non-conventional resource is very important in some areas of Spain. With advanced infrastructure and regulations that promote the circular economy, the country has developed projects that allow the recovery of water for subsequent use in various sectors.

Thus, reclaimed water in Spain is widely used in agriculture (61.9%), where it represents a vital source for irrigation in arid and semi-arid areas. It is also used to irrigate parks and gardens and leisure areas (18%), in industrial processes (17.4%), in sewer cleaning and/or street cleaning (2%) and the recharge of aquifers (0.8%), contributing to environmental sustainability and savings in drinking water.

These uses demonstrate the versatility of reclaimed water and its importance in integrated water resource management, so that water reuse not only relieves pressure on natural water resources, but also offers environmental, economic and social benefits. Here, technology plays a crucial role in the water reuse process, employing advanced treatment systems such as reverse osmosis, ultrafiltration and advanced disinfection to guarantee the quality of reclaimed water and its destination for multiple applications.

In recent years, Spain has seen a significant increase in the volume of reclaimed water, thanks to innovative projects and the continuous improvement of treatment technologies. One of the most notable examples is ESAMUR's integrated water management system in the Murcia region, which has pioneered the use of reclaimed water for agriculture, making a significant contribution to the local economy and environmental sustainability, alleviating pressure on existing water resources.

In recent years, Spain has seen a significant increase in the volume of reclaimed water

In the industrial domain, the success story of Sacyr Agua stands out, which has been in charge of designing and building a WWTP for industrial wastewater for Grupo Alacant, whose processes guarantee the quality of the water for its reuse at all times.

In the islands, EMALSA is now focusing on the reuse of water from Gran Canaria, with special attention to the irrigation of green areas and native crops, where they consider reclaimed water as a viable and optimal resource. Furthermore, Tedagua has an important urban water reuse project for agricultural and urban use in the Balearic Islands, at the Palma II WWTP.

Finally, the case of Canal de Isabel II in Madrid stands out, which in March 2023 exceeded 17 million cubic meters of reused water in the region. With them, it supplied the 26 municipalities that have this service. Each year the utility produces more than 100 hm3 of reclaimed water for irrigation of green areas and industrial uses, as well as for environmental uses, returning it to the rivers in the highest quality.

Reclaimed water reuse is becoming consolidated as a key strategy to address water scarcity in Spain

Challenges and prospects for water reuse in Spain

Reclaimed water reuse is becoming consolidated as a key strategy to address water scarcity in Spain, with a growing focus on technological innovation and stakeholder participation in integrated water resources management. But it is not without its challenges.

Despite advances, water reuse faces challenges, including the need for investment in infrastructure, adapting to increasingly stringent European regulations in terms of reclaimed water quality, and public acceptance.

Nevertheless, water reuse in Spain presents itself as an essential element to address current and future challenges, as it not only helps mitigate the impact of drought and water stress, but also promotes sustainability and efficiency in the use of water resources.