OECD urges Paris to act upon water scarcity

The Paris metropolitan area needs to act effectively in response to increasing water scarcity. This is one of the recommendations of a recent report from the Organisation for Economic Co-operation and Development (OECD). The report provides strategic, technical, and financial recommendations for improving drought resilience across the Île-de-France region.

The OECD-report Adapting the Paris Metropolitan Area to a Water-Scarce Future published in March, states that despite the Paris region benefiting from historically high rainfall, remains vulnerable to more frequent droughts. Climate projections estimate a 10–25% drop in summer rainfall by 2050. However, socio-economic development is also a driver of future drought risk with urban expansion hindering aquifer discharge and groundwater storage. The report calls for a systematic overhaul of how the region manages and plans for water scarcity.

Improved drought risk assessment

The first recommendation is to develop a robust drought risk assessment framework. This includes better monitoring of water usage and abstraction volumes by type of user. The report recommends the projection of water demand across different socio-economic scenarios. In addition, water supply forecasts need to be updated using the latest climate models. The OECD report also calls for an assessment of activities vulnerable to drought, such as agriculture and fluvial transport. It proposes defining acceptable levels of risk, such as minimum river flows for ecosystems or critical supply thresholds for drinking water. Key to improving awareness and preparedness of the situation is increased public communication of the risks, the report suggests.

A coordinated strategic framework

The report highlights the need for a cross-sectoral, long-term strategy for drought resilience. This should be rooted in updated risk assessments and remain flexible to adapt to evolving climate trajectories. Coordination between municipalities needs to be improved, the report concludes, particularly to manage upstream-downstream water issues and ensure coherence between urban and peri-urban areas. Policy coherence is another key element. Water resilience planning must be integrated with regional economic development, climate change strategies, urban planning, and agricultural and industrial policy. The OECD wants authorities to engage stakeholders across sectors and define roles and responsibilities within resilience plans.

Water-saving measures

Furthermore, the report calls for the promotion of sustained awareness campaigns to encourage water-saving practices outside times of drought. The support of efficient technologies, such as household water-saving kits and improved irrigation systems in agriculture, could see an improvement in uptake.

Existing water allocation tools, including permits and drought-related waivers, should be used to incentivise long-term reductions in water withdrawal. Collaborative efforts like the Aqui’brie project and farmers’ associations are highlighted as examples of successful demand-side engagement.

Water supply optimisation and reuse

On the supply side, the report recommends conducting water consumption diagnostics to determine where supply-side measures are needed to complement conservation. Efficiency in municipal networks should be a priority, as well as monitoring leaks in private networks. The OECD advocates for integrating greywater reuse into regional regulations and increasing the use of rainwater harvesting in new buildings where appropriate. The report also encourages the use of nature-based solutions. Mapping ecosystem services can identify priority areas for actions such as reforestation and wetland restoration to support natural aquifer recharge.

Financing drought resilience

Finally, the report calls for a comprehensive financing strategy to underpin these measures. This should include estimating public investment needs across all levels, river basin, regional, and municipal, and identifying funding sources. Aligning public spending with resilience goals is essential, particularly through the Green Fund, the Major Natural Risk Prevention Fund, and infrastructure operators.

Ongoing efforts in Paris

The OECD’s recommendations build on major water investments already undertaken in Paris. Before the 2024 Olympic Games and to comply with the EU Water Framework Directive, Paris completed extensive works to improve the water quality of the Seine. These included a new underground stormwater reservoir near Austerlitz and the redevelopment of the Saint-Michel wastewater outlet. However, opposition remains regarding the long-term direction of water treatment technologies. A 2023 proposal to introduce reverse osmosis at Achères faced criticism for its high energy demand and the impact of brine discharges on aquatic environments.