Q&A

We are planning to invest £340 million to build a new reservoir in Havant, Hampshire. It is being built in collaboration with Southern Water and will help secure more reliable and resilient water resources for our area and the wider South East.

The South East, as a whole, is under ‘serious water stress’ and water companies are being asked to take less water from some of their sources – such as the chalk rivers in Hampshire – to keep them healthy and protect wildlife. 

At the same time, water companies need to find more water to cater for the effects of climate change and a growing population. 

This major change is going to particularly affect Southern Water, which needs to find new water resources for the customers it supplies drinking water to in Hampshire, to replace water taken currently from the River Test and the Itchen.

In Portsmouth Water's area, there are underground springs which provide plentiful, clean water. In winter, much of this water is surplus to requirements and flows out to sea, so we could make better use of some of it by capturing it and storing it in the reservoir until it’s needed. 

This will allow us to share more water with Southern Water’s customers in Hampshire from our network and increase the resilience of water supplies in the South East.

• We already have agreements to share up to 30 million litres of water a day with Southern Water (in West Sussex and Hampshire).
• We can share a further nine million litres a day from 2024 from other sources (Hampshire)
• We can provide an extra transfer from a mix of sources when the reservoir is built, up to 21 million litres a day (to Hampshire)
• The total would be up to 60 million litres of water per day provided to Southern Water.

Overall, building the reservoir would make the whole South East much more resilient to droughts, which are likely to happen more often in the future due to climate change.

The reservoir would be able to hold about 8.7 billion litres of water when full and supply an average of 21 million litres of water each day.

That’s enough water to supply about 160,000 people during an average year.

As well as being supplied with water from the reservoir, our customers would have the benefit of a new community leisure facility on their doorstep. There would also be a host of environmental benefits locally.

The reservoir site would create a new, healthy and safe place for people to visit – with footpaths for walking, as well as routes for cycling and horse riding, facilities for bird watching, picnic and play areas and car parking.

There would be a visitor centre with a café, toilets and space for community and education activities.

Our proposals for the site so far have been developed over many years with local communities, young people and organisations such as Staunton Country Park and Forestry England.

Building the reservoir would allow us to share water supplies with households in Hampshire (outside of our supply area) who receive their drinking water from Southern Water and where there is a severe shortage.

This means Southern Water’s customers would have reliable water supplies and less water would need to be taken from the River Test and River Itchen, which would be better for the environment.

Our customers in Hampshire who we supply water to are also customers of Southern Water for their wastewater services, so everyone in the area would benefit from the community and leisure facilities at the reservoir.

The reservoir would be about one mile (1.6 km) long from east to west and 0.5 miles (0.8 km) wide from north to south. It would be up to 18 metres deep and have embankments on three sides. The below image shows what the reservoir could loo like when completed and open to the public.

We’re planning to build a visitor centre on the site with a café, toilets and space for education and community activities.

There would also be footpaths for walking, cycling and horse riding, facilities for bird watching, such as bird hides, and picnic and play areas. Furthermore, there would be car parking and cycle racks.

We’re working in partnership with neighbouring Staunton Country Park and Forestry England, organisations we already work very closely with, to make sure the facilities and activities are a good fit with theirs.

Our approach to designing the reservoir has the environment and the community at its heart. Further details are set out below.

Our masterplan covers all the environmental and community factors we are taking into account. This means we’ve considered the environment as we’ve designed every part of the reservoir, the access roads and pipeline, and we’ll continue to do so.

We’re also working closely with Forestry England, who own and look after the neighbouring Havant Thicket woodland, and Staunton Country Park (which is owned and run by Hampshire County Council) to see how we can manage the sites together in the future.

This approach, along with lots of feedback from local communities and environmental organisations, has helped us choose the facilities we’re proposing, namely:

• A wetland habitat to support threatened bird species and provide areas for endangered bat species to find food
• A visitor centre with a café and facilities for communities and schools
• A network of trails and paths for walking, cycling and horse riding, linking to others in the wider area
• New woodland, hedgerows and wildflower planting
• A landscaped parking area for vehicles and bicycles.

The reservoir project will improve existing woodland and create a valuable new wetland, woodland and parkland. A grant scheme will also support wildlife across Hampshire and West Sussex.

Creating the reservoir will help protect the River Test and River Itchen in Hampshire. By using the reservoir to supply our own customers, we can share supplies from our other water sources with Southern Water. This means they will be able to reduce the amount of water that they take from these rare and sensitive chalk streams, which are home to many species.

We would need to remove 12.5 hectares of ancient woodland to build the reservoir and we have reduced this as much as possible by changing the design. We’re committed to replanting and improving around 200 hectares of woodland and pasture both on and around the site and further afield to leave an overall positive gain for the environment and communities.

Timeline

The reservoir will take nine years in total to plan, design and build and is scheduled to be complete, full of water and open to the public by 2029.

A huge amount of work has already been completed to share information, draw up detailed plans, carry out environmental mitigation work and prepare the site for building work

This diagram below sets out our timescales, with construction taking place in phases.

Construction

The task of building the reservoir is a large one which will take a number of years. It will involve the combined expertise of a team of engineers, planners and a large workforce to complete this major project. As the site is in a natural valley and made up of clay, we expect to be able to dig this to shape the reservoir without having to bring in extra material or remove it. During the construction we would liaise regularly with communities to keep disruption to a minimum and create opportunities for local employment and education.

Projected timeline

2021-2022:

• Ongoing creation of new woodlands and habitats for wildlife migration
• Prepare planning applications for the detailed design of the reservoir operational and visitor facilities, access and recreational routes and the pipeline route
• Build the access roads
• Start work to prepare the site
• Divert paths
• Community engagement.

2023 – 2026:

• Dig out the clay and move it within the site to shape the reservoir bowl
• Build the embankment
• Lay the pipeline which will transfer the water from the springs to the reservoir
• Community engagement.

2027 – 2029:

• Create a new network of paths
• Pump water from the springs to fill the reservoir (during winter)
• Build the visitor centre and other facilities
• Open to the public.

Since 2019, we’ve carried out a range of activities to raise awareness about the reservoir and encourage people to find out more and tell us their views. This has included: 

• Sending out a letter from Portsmouth Water CEO Bob Taylor in October 2019 to 27,000 local homes and businesses to tell them about the reservoir and direct people to where they can find out more
• Carrying out customer research to gauge people’s attitudes on the reservoir, with the vast majority of those surveyed supportive of the project
• Setting up a dedicated Facebook page and these web pages for Havant Thicket Reservoir, making it easier for people to learn more and get in touch to ask questions
• Holding a series of public exhibition events in November 2019, with face to face discussions with residents
• Liaising closely with a wide range of community representatives to get their input into our proposals – e.g. we’ve been talking to local MPs, councillors, council officers, environmental and community groups and organisations like Forestry England and Staunton Country Park
• Holding a public consultation on the reservoir project proposals from 11 May to 8 June 2020.

We have carried out detailed research with people living locally to the proposed reservoir site.

The vast majority, 70 per cent, of those surveyed said they are completely supportive of the reservoir

Almost half of people understand that pressure on water resources is the main ‘driver’ for reservoir

All the planned leisure activities at the reservoir site are supported to some extent, with people’s top three priorities being a picnic and play area, dog walking and walking / running facilities

There’s lots more information on this website, where you can also give us your questions and comments using the 'Ask us a question' tool on each page. 

You can also get in touch with us via email, phone or post. See our Get in touch page for more.