Athens is a city shaped by history, but today its future is increasingly shaped by climate pressures. Home to a third of Greece’s population and welcoming up to 10 million visitors each year, the metropolitan area relies on drinking water transported from reservoirs as far as 190 kilometres away. Extended droughts, intensified heatwaves and declining winter snowfall have placed the city’s water supply under mounting strain, with reservoir levels dropping to 60% of their capacity.
To safeguard future supplies, the Athens Water Supply and Sewerage Company (EYDAP) is investing €2.1 billion in new infrastructure, conservation efforts and innovative technologies. Among these solutions is a decentralised sewer mining unit developed with experts from the National Technical University of Athens (NTUA) and the EU research project IMPETUS.
A new approach to local water reuse
Installed in the community park of Markopoulo, a town south of Athens Airport, the sewer mining plant connects directly to the municipal sewage system. It filters and disinfects wastewater in stages, producing high-quality water suitable for irrigation, aquifer recharge, and additional uses such as firefighting or street cleaning. Around 25 cubic metres of water are treated and stored daily in a subsurface tank, with EYDAP conducting regular safety checks.
EYDAP’s Katerina Dimitrou, who oversees new activities at the company, says the aim is ambitious: to eventually use such systems to irrigate every park in the wider Attica region. The model unit in Markopoulo serves as both a technological demonstrator and an opportunity to build public confidence in water reuse.
Designing for public acceptance
Integrating the unit sensitively into the park was the responsibility of architect Maria Petinaki, a specialist in ecological building techniques. The structure uses recyclable and natural materials and operates autonomously thanks to rooftop solar panels.
Mayor Konstantinos Allagiannis emphasises that sustainability and circularity guided the municipality’s decision to host the project. The positive experience has encouraged the town to explore additional applications across local green spaces and agricultural areas.
Digital innovation for regional water planning
Beyond the treatment unit itself, the system is monitored through a network of sensors feeding real-time data into NTUA’s control room and onward to a digital twin representing the wider Attica region. This 3D virtual model incorporates environmental data and allows researchers to simulate pressures, test scenarios and plan long-term interventions.
“Having a digital twin is important,” says Professor Christos Makropoulos from NTUA’s School of Civil Engineering and partner in the IMPETUS project. “We can understand in real time how the environment responds, and explore how climatic pressures and management decisions interact. The technology can be expanded and transferred to other regions across Greece and Europe.”
A scalable model for a changing climate
Although modest in size, the Markopoulo sewer mining unit offers a glimpse of a more resilient future. By reusing wastewater locally, Athens reduces its dependence on distant reservoirs, easing the pressure on the wider water system. Combined with advanced digital modelling, this approach provides a replicable pathway for cities striving to secure their water supplies in a warming world.
