The £16m deal covers early-stage design and planning for nitrogen reduction works at Portswood WwTW near Southampton and the installation of UV disinfection at Thornham WwTW near Havant.

At Portswood, Kier will develop solutions to meet a new nitrogen discharge limit of 9mg/l by 2030, working within tight site constraints by repurposing existing infrastructure and expanding sludge and tertiary treatment.

At Thornham, a UV disinfection system will be installed to improve shellfish water quality by 2027, with longer-term plans to expand capacity for population growth – including the option to switch to an activated sludge process and build new assets south of the site.

The schemes aim to strengthen resilience, support regulatory compliance and enhance environmental performance, building on Kier’s growing water sector portfolio with recent wins at Severn Trent, Anglian Water and Wessex Water.