Relocating Guildford sewage treatment works
We've agreed to relocate our Guildford sewage treatment works (STW). This is so the development of the new Weyside Urban Village can take place. The move is in agreement with the Guildford Borough Local Plan.
The project will include 1,500 new homes and new community facilities. It will also help improve the local area with 6,500m² of commercial space.
Guildford Borough Council is funding the relocation project. We’re working closely together to ensure a smooth overlap on both our projects. Our remediation strategy has been approved by the planning authority and stakeholders.
We'll update this page with how the project is progressing.
Construction update (Autumn 2026)
Construction has been going well since starting this project. Work we've done so far includes:
- Over 1,500,000 hours of work completed
- 14,000m3 of concrete poured
- All treatment process structures completed
- 3,500 pre-cast piles and 7,500 inclusion piles installed
- 1.4Km tunnel drive and shafts completed
- Outfall pipes and headwall at the River Wey completed
- New administration building work largely complete
- Underground infrastructure (pipework and ducting) work completed
- Installation of mechanical equipment completed
- Above ground pipework installation largely complete
Our focus now is completing the electrical installation and testing. This will make sure we're ready to start commissioning the new plant at the beginning of 2027.
We expect the works to be fully complete and operational in Autumn 2027.
Project gallery
We've gathered photo highlights from across the project, from foundations and tunnelling to treatment infrastructure.
Innovative methodology to compact the site and prevent long term settlement
Driving pre-cast concrete piles into the ground to provide stable foundations for the structures
Tunnel boring machine (named Daphne by a local school) at its end point after covering 1,400m
Regular structures are manufactured in factories and then assembled on site. Complex structures are expertly built on site using formwork, steel reinforcement and concrete
Whilst verifying the integrity of our new structures, test water is recycled on site. This reduces demand on precious resources and cuts down our carbon footprint.
The sludge treatment area and odour control system is nearing completion of dry testing. When sludge is produced (next year), it will be treated before being taken off site to be converted into energy
Delivering long-term value for customers and communities
We're increasing wastewater treatment capacity, supporting future growth and enhancing the local environment, while minimising impacts on neighbouring communities during construction and operation.
Benefits of the project
- Capacity for treatment of wastewater will be increased for a population of at least 120,000
- The site will have space for future expansion. This will be in line with modelled growth and the impact of climate change
- Our proposal will result in 10% net gain in biodiversity value
- Minimising the long-term visual impacts of the site. We'll do this by improving and supplementing the north trees which screen the site
How we're working to reduce impact
- We’re using the latest odour control methods to minimise any impacts on our neighbours
- Our new discharge location will not impact the flooding potential in the River Wey. We’re providing increased storm capacity
- Work will not impact the nearby allotments. Mitigation will be in place to reduce the impact of noise or light during construction
- There will be no increase in traffic once the site is operational. Construction traffic will avoid peak hours where possible
How we'll build our new STW
Our relocation project has three key elements and will be done in four phases:
Phase 1: Ground improvement
This work was completed in February 2025.
We've successfully finished this phase having stabilised the ground and installed over 10,000 piles.
Phase 2: Civil engineering
This work completed in August 2026.
All of the structures have now successfully been completed.
We have used pre-cast concrete panels for quite a few of the structures. They were built off-site and then assembled on-site later. This was a quicker method, safer, involved fewer deliveries, and created less noise as a result.
Phase 3: Mechanical and electrical engineering
From Autumn 2024 to December 2026.
We have been receiving and installing various mechanical and electrical equipment. This has started to be installed on site.
During this phase, there will be minimal disturbance to our neighbours.
Phase 4: Commissioning
Winter 2025 to Spring 2027.
The new STW will start to become operational and the existing STW will be taken out of service. During this phase, there'll be minimal disturbance to our neighbours.
Get in touch
If you have any questions or concerns, please get in touch. Call us on 0800 316 9800 selecting option 1 and quoting BB01235981.
For business customers, please contact your retailer for additional information.