Barcelona’s bold water-saving move

Greywater plan for Barcelona

Shower water to be reused for toilet flushing. Credit: Volurol/Shutterstockcom

The Barcelona City Council has set the wheels in motion for an innovative ordinance aimed at conserving water in a novel way.

Scheduled for approval by the end of 2024, this pioneering regulation mandates the installation of greywater recycling systems in new and extensively renovated buildings.

The scheme will be aimed at structures with more than 16 dwellings or those exceeding an annual shower and bathtub water consumption of 500 m³, the ordinance represents a significant step towards sustainability.

‘The everyday gesture of flushing the toilet is a small ecological disaster,’ the council noted, highlighting the urgency of this initiative.

What exactly is Greywater recycling?

Greywater recycling refers to the treatment of wastewater from appliances such as showers, baths and sinks, to be re-used and fed back into a property for non-potable purposes such as flushing toilets.

With an average Barcelonian using 35 litres of water daily just for toilet flushing, the potential savings from this initiative are substantial.

The council anticipates a 30 per cent reduction in water usage citywide, equivalent to saving 300,000 m³ of water per year.

‘If all buildings in Barcelona had it installed, 30 per cent water would be saved,’ they stated, underscoring the effectiveness of greywater recycling.


The implementation of this system is not just environmentally friendly but also economically viable. A modest investment in a greywater treatment plant for each building promises quick financial returns.

‘The investment to install this system “is minimal” and that it is recovered quickly,’ the council assured, estimating an annual saving of about €90 per household due to reduced water consumption.

Forging ahead with innovation

This initiative builds on existing efforts in districts like Gracia and the 22@ area, where new buildings are already required to incorporate greywater systems.

Barcelona ‘must continue to reduce and optimise drinking water consumption,’ said Oriol Altisench, the council’s chief engineer, emphasising the city’s commitment to sustainability.

With the ordinance still in the early stages of development, the council is opening a participatory process to refine the proposal. The ultimate goal is to establish a framework that guarantees the quality and sustainable use of recycled greywater, ensuring Barcelona remains at the forefront of environmental stewardship.

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Written by

John Ensor

Originally from Doncaster, Yorkshire, John now lives in Galicia, Northern Spain with his wife Nina. He is passionate about news, music, cycling and animals.