The Havant Thicket Reservoir in Havant, a collaboration between Portsmouth Water and Southern Water, is designed to safeguard water resources for the South East for years to come.
It will be an 8.7 billion litre storage reservoir spanning 160 hectares in between Leigh Park, Havant and Rowlands Castle in East Hampshire.
The planning application for the reservoir, along with a separate one for the pipeline which is needed to fill and remove water to supply to customers, was considered and granted permission by councillors at Havant Borough Council and East Hampshire District Council in 2021.
Havant Thicket Reservoir could open fully to the public in 2029.