Delivering the first new freshwater storage reservoir in the UK in more than 30 years
Our engineers and water experts have been working on Portsmouth Water’s Havant Thicket reservoir project in Hampshire, United Kingdom, which marks the construction of the first new reservoir in the country since Severn Trent Water’s Carsington Reservoir in Derbyshire was built in 1991. Havant Thicket Reservoir is intended to facilitate a water transfer to local utility provider Southern Water (serving West Sussex and Hampshire) under a Bulk Supply Agreement. GHD’s role oversees the design of major civil and structural elements, including the reservoir, valve tower and culvert, spillway, viewing platforms and site infrastructure. We are working to deliver the project alongside collaborative design partner Coffey UK.
This contract recognises GHD's global expertise in reservoir and dam engineering, along with a rich history of experience in the UK, particularly in delivering designs for critical water supply infrastructure. Notable examples include GHD’s contributions to the Severn Trent’s Birmingham Resilience Programme and United Utilities' Oswestry Water Treatment Works.
Havant Thicket reservoir
Aligning with GHD’s longstanding commitment to sustainability, the project aims to secure a reliable and sustainable water supply for customers in Southeast England, an area suffering increasingly from acute water stress due to climate change and surrounding population growth. Southern Water is actively engaged in protecting two of the UK's rarest chalk streams, the River Test and the River Itchen, by reducing their water extraction. As a result, Southern Water must identify fresh and sustainable water sources to maintain the continuous provision of water to its customers in the Hampshire region.
Many natural springs in the Havant area provide 30 percent of the company’s water, delivering a steady, high-quality water supply throughout the year. These springs are considered the largest individual source of spring water in Europe. In the winter and during periods of high rainfall, an excess of water from the springs surpasses Portsmouth Water’s own customer requirements. This surplus is then discharged directly into the sea. To optimise the utilisation of this surplus water, it will be stored in the Havant Thicket Reservoir, enabling Portsmouth Water to share water from its network with Southern Water, enhancing water supply resilience across the entire region.
Creating the reservoir will help protect the River Test and River Itchen in Hampshire. This £120 million project, funded by Portsmouth Water in collaboration with Southern Water, is on track for completion in 2028. It is designed to accommodate approximately 8.7 billion litres of water and deliver a daily supply of 21 million litres.
The Havant Thicket Reservoir is a vital piece of infrastructure for the region, and we are excited to have been chosen to oversee its design. Southeast England is under serious water stress, and our experience designing large-scale infrastructure projects will help deliver the reservoir successfully. Sustainability sits at the heart of GHD’s approach, and we are honoured to have the opportunity to make a long-lasting impact on the local area through this project. We look forward to working on the reservoir and contributing to its success.”