Knowledge Framework
Use Cases
- Reduce water demand during shortages — Implement restrictions, campaigns, and pricing measures to cut water consumption when supply is r...
- Treat wastewater for safe reuse — Take treated sewage effluent through additional advanced treatment to produce water safe for irri...
Decision Patterns
- Demand reduction programmes — Reduce water usage behaviourally
- Water reuse systems — Treat wastewater for reuse
System Models
Water quality models
Tool: Integrated urban water cycle models — Models reuse flows and water quality compliance
Overview
Barcelona experienced a severe drought crisis in 2007–2008 that brought the city within weeks of emergency water rationing for its 5.5 million metropolitan residents. Reservoir levels fell below 20%, and the regional government was forced to import water by tanker ship from Marseille and Tarragona.
This crisis catalysed investment in water reuse infrastructure as part of a broader supply diversification strategy. Barcelona now operates three major tertiary treatment plants that produce reclaimed water for non-potable uses including municipal irrigation (parks, gardens, street cleaning), agricultural irrigation, industrial cooling, aquifer recharge, and environmental flow maintenance in the Llobregat and Besòs rivers.
The programme aims to achieve 25% reuse of treated wastewater, reducing demand on potable supply sources and creating a more circular urban water economy.
Timeline & Location
2007–2008: Severe drought; reservoirs fall below 20%. Emergency water imports by tanker ship. 2009: El Prat de Llobregat tertiary treatment plant expanded. 2010s: Reclaimed water distribution network extended across the metropolitan area. 2012: Managed aquifer recharge programme begins in the Llobregat Delta aquifer. 2015: Barcelona Cicle de l’Aigua (Water Cycle) strategic plan adopted. 2020s: Further expansion of reuse capacity and distribution network. Integration with Barcelona’s desalination plant (El Prat, 200,000 m³/day capacity).
Stakeholders
The Àrea Metropolitana de Barcelona (AMB) oversees metropolitan water services. Aigües de Barcelona (AGBAR), part of the Suez group, operates the water supply and treatment system under a concession. The Agència Catalana de l’Aigua (ACA) is the Catalan water authority responsible for river basin management.
Agricultural users in the Llobregat Delta and Besòs valley receive reclaimed water for irrigation. Municipal parks and gardens departments are major users. The programme supports environmental flows to maintain river ecology, particularly in summer low-flow periods.
Digitalisation & Data
Barcelona’s water system is managed through a smart water network with over 500 sensors monitoring flows, pressure, and water quality across the distribution system. SCADA systems control the tertiary treatment plants and reclaimed water distribution. Real-time water quality monitoring at key reuse points ensures compliance with health and environmental standards.
Hazards
Exogenous Hazards
Climate change projections indicate 15–25% reduction in water availability in the western Mediterranean by 2050. Increasing drought frequency and intensity. Tourism seasonality creating peak summer demand coinciding with lowest water availability.
Endogenous Hazards
Public perception barriers to water reuse (particularly for any future potable reuse). Ageing distribution infrastructure in the old city. Energy costs of tertiary treatment. Emerging contaminants (pharmaceuticals, microplastics) in treated wastewater requiring advanced treatment.
Cost & Benefit
Cost: Tertiary treatment adds approximately €0.15–0.30 per cubic metre above conventional wastewater treatment costs. The reclaimed water distribution network required significant capital investment. Barcelona’s desalination plant cost approximately €230 million.
Key Benefits: Reduction in potable water demand by substituting reclaimed water for non-potable uses. Drought resilience through supply diversification. Environmental benefits through maintained river flows and aquifer recharge. The Llobregat Delta aquifer recharge programme provides a natural underground water storage buffer.
Resilience Principles Assessment
Assessment of meeting Principles of Resilient Infrastructure
Environmentally Integrated (P3)
Reclaimed water maintains environmental flows in the Llobregat and Besòs rivers during dry periods when natural flows would be insufficient. Managed aquifer recharge uses natural filtration processes. The programme reduces wastewater discharge to the Mediterranean.
Proactively Protected (P2)
The post-2008 diversification strategy proactively protects Barcelona from future drought by reducing dependence on rainfall-fed surface water through desalination, reuse, and aquifer recharge.
Adaptively Transforming (P6)
The 2008 crisis transformed Barcelona’s approach to water management from supply-dependent to diversified and circular. The city now has multiple drought-independent water sources.
Shared Responsibility (P5)
Metropolitan-wide governance through AMB coordinates water management across 36 municipalities. Public-private partnership with AGBAR delivers operational efficiency. Water costs are shared across the customer base.
Continuously Learning (P1) To Do
Details pending.
Socially Engaged (P4) To Do
Details pending.
Futures
Barcelona is expanding its reuse programme towards the 25% target and exploring the feasibility of indirect potable reuse through aquifer recharge. Integration with the desalination plant provides additional drought insurance. The EU Water Reuse Regulation (2020/741) provides a harmonised framework for agricultural reuse across Europe.