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Woolston Wastewater Treatment Works

At the end of 2020, the transformation of Woolston Wastewater Treatment Works was completed after a £100 million-plus investment from Southern Water.


The existing site was built in 1966 and was in need of modernisation. The redevelopment project, which started in 2014, will:

  • reduce smells coming from the site
  • ensure the treated wastewater leaving the site meets new, higher environmental standards
  • ensure the redesigned works fits in with the ongoing redevelopment of the area.

The new treatment works will service the area long into the future. The film below gives a 3D virtual tour of the site.

Reducing smells

The new treatment works at Woolston will significantly reduce the smells coming from the site and we’re already seeing a positive effect.

Previously, the site used open air tanks– which is where the majority of smells came from. These have been replaced with new treatment processes that are fully odour-controlled and contained within the building.

Connecting with the community

As agreed with local community groups and Southampton City Council, we created a Community Liaison Group. This allowed us to receive feedback from the community and provide progress updates – so we could keep everyone updated about our works. This was chaired by Woolston Councillor, Warwick Payne.

Approach to construction

We started work in September 2014. The work was carried out by 4Delivery (4D) – a consortium comprising Veolia Water, Costain and Stantec – on behalf of Southern Water.

This major project was carried out in stages to ensure we could continue to treat wastewater for the local area while the new site was being constructed. A temporary treatment works was constructed. This enabled us to start work on the existing site by demolishing tanks and old structures.