Havant Thicket Reservoir: What's Being Built & When

What is the Havant Thicket Reservoir?

Havant Thicket Reservoir is a new water storage reservoir being built by Portsmouth Water in partnership with Southern Water, near Rowlands Castle. Havant Borough Council's project page describes it as an 8.7 billion litre reservoir spanning 160 hectares between Leigh Park, Havant and Rowlands Castle in East Hampshire. The project's own website says its purpose is environmental: Southern Water is cutting the amount it takes from the River Test and River Itchen, and Portsmouth Water's large Havant springs can provide surplus winter water that would otherwise flow out to sea, to be stored in the reservoir and shared with Southern Water.

The project site calls it the first large-scale new water storage reservoir in the UK since the 1980s.

Planning permission and who decided it

According to the project's planning and construction page, East Hampshire District Council's Planning Committee resolved to grant planning permission on 9 June 2021, after Havant Borough councillors supported the proposals on 3 June 2021. Havant Borough Council says a revised pipeline application was approved in May 2025 and that further applications have since been made to sign off final design details, which can be searched on its public register using the keyword Havant Thicket Reservoir.

The scheme was a hybrid proposal. Parts such as the embankment, access points and viewing areas were submitted in detail, while the wetland, control house, visitor centre and car park, access routes and recreational facilities were outline, with designs described as illustrative for now.

Timeline: what has been officially published

The dates on the project's pages do not all agree, so read them with care. The planning and construction page still says the reservoir is due to be completed and operational by 2029. The more detailed construction timeline page says main construction began in spring 2025 and that, when completed in the early 2030s, Portsmouth Water will take water from the reservoir during a drought. It also says the shared-pipeline approach means the reservoir will be finished later than originally planned, with an updated timescale to be confirmed, and that regulator Ofwat must approve the planned costs. No single opening date is confirmed.

Recent news on the latest news page includes a February 2026 milestone, when a 20 tonne steel Culvert Cut Off Wall was installed over 72 hours, with the main embankment due to be built over it later in 2026, and a May 2026 announcement that work was about to start on two new pipelines, due to complete by 2029 over three years. The pipelines route is 7km, each pipe 1.7m in diameter, and Portsmouth Water says they will carry 40 million litres a day to the reservoir.

Roads, footpaths and access

The project has planning permission for two access routes. The access routes page says the northern route comes from the A3(M) Junction 2 via the B2149, uses a single-track road, is intended for most construction vehicles and visitors from further afield, and was chosen partly because it avoids residential areas in Warren Park and Rowlands Castle. The southern route comes off Swanmore Road and is mainly for local communities. Both are designed to end in the site's car park, to avoid a rat run.

The pipelines will be installed mainly by micro-tunnelling to avoid digging up roads and pavements. Two shorter sections will be open cut, through Hooks Lane playing fields in Bedhampton and open space at Staunton Country Park up to the reservoir. For specific closures, use the project news page.

Planned visitor facilities

The project's community, education and leisure page says plans include paths for walking, cycling and horse riding extending about 5km around the reservoir and fully accessible, picnic and play areas, and bird watching facilities. A visitor centre is proposed with an information and education area, cafe and toilets, and the project is working with Staunton Country Park and Forestry England. These are plans, not open facilities, and the reservoir is not open to the public. For a visit now, try Queen Elizabeth Country Park or our walking routes from Horndean.

The water recycling proposal

The approved plan has no recycled water in it. The project says Portsmouth Water and Southern Water have been exploring adding highly treated recycled water to the reservoir, which it says would secure up to 90 million litres a day extra. The proposals, known as the Hampshire Water Transfer and Water Recycling Project, are subject to further public consultation, regulator approval and planning permission. The new pipelines are being built to be shared, but the project says they will not carry recycled water unless and until that project is approved and built. Havant Borough Council's page points to Southern Water's Water Recycling Project. Check Southern Water's website for its current position.

Where to follow updates

The project's website has a news page, an interactive pipelines map and an e-newsletter sign-up, and says updates also appear on the reservoir Facebook page and X. Planning applications can be searched on Havant Borough Council's register. Our Rowlands Castle guide has more on the village.

Quick answers

When will Havant Thicket Reservoir open? Not confirmed. The project says completion is in the early 2030s and that an updated timescale is to be confirmed, though one page still says 2029.

How big is it? 8.7 billion litres over 160 hectares, per Havant Borough Council.

Will it use recycled water? Not under the approved plan. Recycling is a separate proposal needing consultation, regulator approval and planning permission.

Where do I find updates? The project's website, its news page and e-newsletter, and Havant Borough Council's planning register.