The next steps for AIGUANEIX on the Costa Brava
The AIGUANEIX project, consolidated in Roses through the wastewater treatment plant and the pilot facility, is now moving into a new phase aimed at bringing about a structural transformation in drinking water supply management in the northern Costa Brava.
In recent years, the Costa Brava Girona Water Consortium (CACBGi) has focused on moving towards a more circular, resilient and locally based system in which reclaimed water becomes a strategic resource. This paradigm shift involves no longer viewing treated wastewater as waste, but rather as a valuable resource for producing purified water intended for coastal aquifer recharge.
The experience gained through AIGUANEIX has made it possible to validate this new system and establish the foundations for future actions. The scalability of the pilot plant and the consolidation of new water sources are the first steps beyond AIGUANEIX, with the projects in Llançà and Cadaqués now taking centre stage.
Llançà: towards a full-scale WPP and aquifer recharge
Following the pilot experience developed at the Roses Wastewater Treatment Plant (WWTP), the next key step is the construction of a full-scale Water Purification Plant (WPP) in Llançà, together with the infrastructure required for coastal aquifer recharge. The future facility will integrate the six purification stages already tested —chloramination, ultrafiltration, reverse osmosis, advanced oxidation, activated carbon filtration and remineralisation— with the aim of producing water of suitable quality for controlled infiltration.
Available data highlight the potential of this approach. The average annual volume of treated wastewater over the last three years is around 670,000 m³/year in Llançà, 420,000 m³/year in Cadaqués and 2,800,000 m³/year in Roses. A significant part of these volumes, which are currently discharged into the sea, could be transformed into a useful resource to strengthen local aquifers.
Cadaqués: towards an agreement with the Catalan Water Agency
At the same time, the CACBGi has initiated the procedures required to sign an agreement with the Catalan Water Agency (ACA) in order to develop a similar solution in Cadaqués. This municipality is particularly sensitive, with aquifers affected by depletion and salinisation episodes, as well as significant seasonal pressure. Purification and aquifer recharge are therefore considered key tools to strengthen water autonomy and reduce external dependencies.
A strategic resource to reduce pressure on the Darnius Boadella reservoir
The use of purified water and its movement through aquifers also has a direct impact on the overall water supply system. If part of the treated volumes is allocated to aquifer recharge, the need to abstract water from the Darnius Boadella reservoir is reduced. This would help extend the availability of stored water, especially during drought periods, while moving towards a “zero-kilometre water” model that is more efficient and better adapted to the territory.
The graphical information associated with the project clearly illustrates this potential: during the 2021-2024 drought period, the accumulated volumes of treated wastewater discharged into the sea in Roses, Llançà and Cadaqués exceeded 15 hm³ combined. Even if only partially reused, this represents a considerable resource that could play a significant role in the respective water supply systems.
Strategic vision and next steps
The CACBGi’s vision is to consolidate this model as a benchmark for circular water management, based on aquifer protection, institutional cooperation and the possibility of replicating it in other municipalities facing similar challenges. The next steps include completing the drafting of the Llançà projects, advancing the agreement with the ACA for Cadaqués and assessing the progressive extension of the model to other municipalities managed by the Water Consortium.
AIGUANEIX is therefore evolving from being merely an experimental project into the first building block of a profound transformation in water management in the northern Costa Brava region, fully aligned with climate change challenges and guided by a clear long-term vision.
“The future Llançà plant will integrate the six purification stages with the goal of producing water of suitable quality for controlled infiltration”
“The use of purified water and its movement through aquifers reduces the need to abstract water from the Darnius Boadella reservoir and would help extend the availability of stored water”
