Joint venture with Cadagua strengthens UK water infrastructure portfolio
By Staff Reporter
London | February 27, 2026
Ferrovial has secured a new contract with Thames Water to upgrade the Slough Sewage Treatment Works (STW), further expanding its footprint in the UK water infrastructure sector.
The project, valued at approximately £80 million, will be delivered through an integrated joint venture between Ferrovial Construction and Cadagua. The scheme reinforces Ferrovial’s long-term commitment to resilient and sustainable infrastructure across the UK.
Project Scope and Environmental Objectives
The Slough STW upgrade is designed to meet updated wastewater quality standards set by the Environment Agency, while enhancing operational efficiency and system resilience.
Key components of the upgrade include:
- Expansion of treatment capacity to comply with stricter quality permits
- Reduction of ammonia and phosphorus levels in treated effluent
- Improved storm permit compliance through better management of high-strength return flows
- Installation of new power supply infrastructure and standby systems to strengthen operational resilience
Upon completion, the enhancements are expected to significantly improve local watercourses, contributing to cleaner and healthier ecosystems.
Design work commenced in November 2025, with construction scheduled to begin approximately 15 months later.
Building on Established UK Experience
The new contract builds on Ferrovial Construction’s established partnership with Thames Water, including the successful delivery of the central section of the Thames Tideway Tunnel.
Over the past two decades, Ferrovial Construction has delivered several major UK infrastructure projects, including:
- Silvertown Tunnel
- Northern Line Extension
Cadagua complements the joint venture with over 50 years of technical expertise in Spain and extensive international experience in water treatment, wastewater processing, and desalination facilities.
Strategic Significance
The Slough STW project represents a key step in Ferrovial’s strategy to combine global technical expertise with local project delivery. As regulatory standards tighten and climate resilience becomes increasingly critical, investment in wastewater treatment infrastructure remains central to the UK’s environmental agenda.
By strengthening treatment capacity and improving environmental compliance, the scheme supports Thames Water’s broader objectives of safeguarding public health, protecting natural waterways, and delivering sustainable water services to communities.
