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.

We first received planning permission for the reservoir back in 1964 and we carried out a lot of work towards a new planning application in 2008.

However, at the time there wasn’t enough demand for the water, either from our customers or across the South East.

Since then, Southern Water has agreed to reduce the amount of water it takes from the Rivers Test and Itchen in Hampshire, to protect the environment, so they need to find new sources.

As a result, we’re now working in partnership with Southern Water to go ahead with the reservoir to secure more reliable water supplies for the region as a whole. It will also help cater for a growth in the population and housing and more droughts as a result of 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.

It would cost about £340 million to plan, build and fill the reservoir with water.

The scheme will be funded by payments from Southern Water to purchase the water it needs to supply its customers. Southern Water has considered a number of options to supply water to its customers and the reservoir is considered to be good value.

Only Southern Water customers who receive drinking water supplies from them will have the cost of the reservoir reflected in their bills. So, this does not include our customers who receive drinking water from us and wastewater services from Southern Water.

Portsmouth Water already has among the lowest water bills in the country (£100 on average).

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.

It’s important we make the best use of the supplies we already have, so we can leave as much water as possible in rivers and the ground to support our environment and wildlife.

Filling the reservoir with water which would normally flow out to sea in winter is one way to do this but we’re also planning to become more efficient with our existing supplies.

Metering

We’ll also be encouraging more customers to have water meters installed – particularly where this will save money on their water, wastewater and energy bills. We’re planning to install 3,000 ‘smart’ meters by 2025 to give customers much more information on their water use and opportunities to save. Find out more about switching to a meter by clicking here.