Thames Water appoints Kier to upgrade the Maple Lodge treatment works

Thames Water has appointed Kier to upgrade Maple Lodge Sewage Treatment Works near Rickmansworth under its AMP8 investment programme. What has been awarded so far is an Early Contractor Involvement contract worth £8.7m; the source puts the overall scheme at £265m — only the ECI figure is a contract value for Kier. The works treat the wastewater of almost 500,000 people across west Hertfordshire; the upgrade adds treatment capacity and new storm storage and is to be carried out while the site stays fully operational. The source gives no construction timetable. Announced on 07.08.2026 (ECI contract). Update: according to the award notice of 17.02.2026, the main contract with Kier (estimated at £140m–£280m) runs from 01.04.2026 to 29.03.2030; the contract end date is used here as the planned completion (Smart Water Magazine, 18.02.2026: https://smartwatermagazine.com/news/smart-water-magazine/thames-water-awards-major-upgrade-contract-maple-lodge-stw-worth-ps280).