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Good practice Imported

El Prat–Llobregat Indirect Potable Reuse — River-Augmentation Drought Response for Barcelona (Spain)

Spain · El Prat de Llobregat · See the Spain profile

Evidence: Observational / pre–post Top 27% 53/100 · Ask Evidence Copilot about this practice

Under Catalonia's 2020 Emergency Drought Plan, advanced-treated effluent from the El Prat plant is pumped 8km upstream into the Llobregat River — up to 2 m3/s — before Barcelona's Sant Joan Despí intake, with monitoring shown safe through the severe 2021-2024 drought.

2 m3/s (of 4 m3/s plant capacity)
River augmentation flow
8 km
Upstream pumping distance
58 %
Share of Barcelona demand met by reclaimed+desalinated sources (2023)
~70 %
Besòs river replication completion
El Prat–Llobregat Indirect Potable Reuse — River-Augmentation Drought Response for Barcelona (Spain)

Details

Maturity
Scaling
Promoter
Agència Catalana de l'Aigua (ACA)
Period
2020–present (2021–2024 drought emergency)
Region (NUTS)
ES51
Keywords
water utilities, drought management, indirect potable reuse, river augmentation

Context

Barcelona draws much of its drinking water from the Llobregat River, a source repeatedly strained by Mediterranean drought, culminating in Catalonia's severe 2021-2024 water emergency.

Objectives

Under the Emergency Drought Situations Plan approved by the Catalan government in 2020, augment river flow with advanced-treated reclaimed water to safeguard both drinking-water supply and the receiving river's aquatic ecosystem.

Activities

The El Prat wastewater treatment plant produces advanced-treated reclaimed water and pumps it roughly 8km upstream, releasing up to 2 m3/s (about half of the plant's 4,000 litres/second capacity) into the Llobregat to blend with river flow before it is abstracted and treated again at the Sant Joan Despí drinking-water plant.

Results

A peer-reviewed, multi-year (2021-2024) risk-monitoring programme published in Water Reuse concluded the practice was a 'successful water resilience strategy.' By 2023, desalinated and reclaimed sources together met an estimated 58% of Barcelona's water demand.

Conclusions

The scheme remains legally tied to declared drought emergencies rather than standing year-round policy. A parallel plan to replicate it on the neighbouring Besòs river, intended to eventually cover over 10% of the metropolitan area's drinking water, was still only around 70% built as of the sources reviewed.

Implementation
Indicative cost
High (€500k–€5M) — Advanced treatment plus an 8km upstream pumping infrastructure; specific capital cost not disclosed in source.
Time to results
Medium (1–3 years) — Drought plan approved 2020; operated through the 2021-2024 drought emergency; Besòs replication ongoing (~70% built).
Staffing & skills
Agència Catalana de l'Aigua (ACA) engineers and water-utility operators, environmental and human-health risk-monitoring scientists

Conditions for success

  • declared drought emergency trigger under the 2020 Emergency Drought Situations Plan
  • advanced (multi-barrier) wastewater treatment capacity at El Prat
  • sustained multi-year risk monitoring to validate safety

Common failure modes

  • remains legally contingent on declared drought emergencies rather than standing policy
  • Besòs river replication only ~70% built, limiting redundancy

Where it fits

Governance type
regional water authority (Catalan government, ACA)
Scale
metropolitan (Barcelona)
Income level
high-income, EU

Commonly funded by

ERDF — European Regional Development Fund National / regional programmes

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Data sources

Where this practice's information was retrieved from, and when.

Attachments

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