Ferrovial, a global infrastructure leader, will 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.
It builds on Ferrovial Construction’s longstanding relationship with Thames Water, notably through the successful delivery of the Central Section of the Thames Tideway Tunnel. This new collaboration underpins Ferrovial’s continued investment in resilient infrastructure to meet the evolving needs of communities and the environment.
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. All encompassed with 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 for the scheme began in November 2025, with construction scheduled to begin an estimated 15 months afterwards.
Ferrovial Construction brings a proven track record in the UK, having delivered complex infrastructure projects over the last 20 years, such as 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.
This project represents a significant step in Ferrovial’s strategy to integrate global expertise with local delivery, supporting the UK’s environmental goals and strengthening its water infrastructure for the future.
