Ferrovial has been appointed to deliver the new contract to upgrade the Slough Sewage Treatment Works (STW) for Thames Water. The c.£80 million scheme will be executed through an integrated joint venture between Ferrovial Construction and Cadagua. a Ferrovial company.

The project builds on Ferrovial Construction’s longstanding relationship with Thames Water, notably through the successful delivery of the Central Section of the Thames Tideway Tunnel.

The Slough STW upgrade is designed to meet updated Environment Agency (EA) wastewater quality standards while improving operational efficiency.

Key enhancements include expanding treatment capacity to comply with more stringent quality permits, like reduction in ammonia and phosphorous, and storm permit by improving management of high strength return flows. The project also includes a new power supply and standby systems to bolster resilience and sustainability.

Once the works are completed, watercourses will transform into cleaner and healthier ecosystems. Design work for the scheme began in November 2025, with construction scheduled to begin an estimated 15 months afterwards.

Ferrovial Construction has a proven track record in the UK with the delivery of complex infrastructure projects over the last 20 years, including the Thames Tideway Tunnel, the Silvertown Tunnel, and the Northern Line Extension. Cadagua brings its expertise and capacity, drawing on over 50 years of experience in Spain and decades of international experience in water, wastewater treatment, and desalination plants.