On location with the team behind Havant Thicket, the first reservoir to be built in the UK in 30 years

26 September 2025

Planet Possible host Niki Roach talks to construction managers, environmental advisors and senior leaders about a major infrastructure project to address water supply challenges in the South East of England

It’s easy to feel gloomy about the water resources challenges that the UK will face over the coming decades. Climate crisis, population growth and aging infrastructure are already making an impact on our water supply and will continue to do so. But major infrastructure projects like Havant Thicket, the first new reservoir to be built in the UK since 1972, are an exciting reminder that, when policy, funding and logistics all fall into line, we can rise to these challenges and ignite the imagination of the sector and the public while doing so.

On this month’s Planet Possible podcast, host Niki Roach travels to Havant Thicket, just outside Portsmouth, to learn about the problem the reservoir is being built to solve, its construction process, the project’s environmental mitigation and compensation programme, and its legacy, in terms of both skills creation and amenity value in the local area.

On her walk around this extraordinary construction site, Niki is joined by Terry Fuller, director of project engagement and sustainability for Future Water, the contractor building the reservoir on behalf of Portsmouth Water; graduate environmental advisor Hayley Drane; Portsmouth Water’s communication and engagement lead, Eleanor Shipton, and assistant environment manager, Ruth Frith; construction manager James Hansen; Lizzie Sams, planning and engagement manager for Future Water; Bob Taylor, CEO of Portsmouth Water; and health and safety advisor Ollie Sanderson. You’ll hear from some of them in this edited excerpt of the episode – listen to the full, even more wide-ranging conversation here or search for Planet Possible in your favourite podcast app.

Now, over to Niki and her guests…

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Niki Roach: Tell me about the size and scale of this project.

Terry Fuller: We are looking across the site, it’s about 1.6 km long. It's pretty vast. It will retain nearly 9 billion litres of water when it's completed. That's enough to supply 21 million litres of water a day to about 160,000 customers.

NR: And why this location?

TF: If you were to get a textbook and try to work out the perfect site for a reservoir, this is almost it. It's a great big basin made up of clay, which means we don't have to bring any clay into the site [clay is excellent at retaining water, compared to other types of soil]. It's broadly a basin-type shape, but we do have to build an earth embankment at the downstream face of it to retain the water. It’s pretty secluded, as you can see. There are people that live around here, but they are some distance away from the perimeter of the site, so noise and disruption is less of an impact than it could otherwise have been.

NR: Tell us about how this site is going to operate.

TF: Consistent with the water solutions [being implemented] around the country, you're looking at co-operation between water companies. Portsmouth water bought this site back in 1965 (which was very forward thinking of them at that time) but right now their customers don't need the water. Neighbouring Southern Water customers do. So Portsmouth are building the reservoir, they will operate it and will be selling that water, effectively, to Southern Water and their customers.

NR: How long is it going to take to fill it?

TF: This is one that surprises people: it's going to take about three years. That’s for two reasons: one is that we can't over-abstract water out of the spring water, which is the source of the reservoir water, so we have to only take that water out during the winter months. The other one is a bit more techy: when you build an earth embankment, you can't just fill it up with water and shock it with all that that load. You've got to fill it up in stages, let the embankment adjust to those water pressures, then fill it up to the next stage.

NR: Tell us more about the stress that Southern Water is currently experiencing.

TF: It's immense pressure. They're not going to be able to supply their customers over the next decade or two unless something is done. The reservoir is just one of a basket of measures, along with leakage control and demand management. The South East is one of the most water stressed regions in the country - it's most acutely felt here in terms of the impacts of climate change on water supply, but also population growth in the area as well.

NR: Ruth, from a Portsmouth Water perspective, tell me about what you're doing about the 12.5 hectares of ancient woodland that's been lost because of the build.

Ruth Frith: We've got a programme of mitigation works and compensation works, which is in excess of 200 hectares of habitat improvements and enhancements, both on and off-site. At South Holt Farm we've engaged with the Pig Shed Trust, a conservation charity that is going to manage that site as wood pasture, woodland and grassland for the next 80 years. We have Southly Forest, just down the road – a 72-hectare site of broadleaf woodland. Ecology monitoring, managing the woodland, putting together a conservation management plan, in collaboration with the Hampshire and Isle of Wight Wildlife Trust. Then there were 3.8 km of water courses lost to the footprint of the reservoir, so in collaboration with the Environment Agency and under the Water Framework Directive, we have a mitigation package of 5.5 km of watercourse enhancement within the catchment.

At the beginning of the project, there was a [community] group called Stop the Chop! We worked with them very closely, and they have now come on board. They’ve rebranded as Havant Thicket for Nature and are part of our key stakeholder group. We work with them replanting rescued saplings from the ancient woodland sites and we have an aftercare contractor who's engaged for the next five years or more to look after all the replanting.

NR: Lizzie, how has Future Water engaged with local communities around the build itself?

Lizzie Sams: Prior to the start of construction, there was a lot of discussion about what benefits that we could bring as a contractor to the area, particularly focused on recreation at the reservoir site, but also in terms of education, upskilling and employment opportunities. We do site visits for local schools and we’re also going into those schools, taking part in careers events and looking at fulfilling the CITB [Construction Industry Training Board] criteria for recruitment into construction. We also have an employment and skills plan for the project, which requires us to recruit apprentices and graduates and take on work placements. T levels are a big focus for the local area, and there's a construction course at the local college, so we're really pleased in the next couple of months to welcome back one of our T level placements from last year, who's starting on a construction site management degree apprenticeship.

NR: How many people are working here?

LS: At the moment we're at ‘peak earthwork season’, and we've got about 180 people working on the site. That's made up of about 60 people or so in the office and about 120 out on the rest of the site, in machines, working on the culvert site, managers, engineers, all those kinds of roles.

NR: What do you hope the legacy of the project is going to be?

LS: To leave a positive footprint on the local area, which is an area of quite high unemployment. Things like our employment and skills plan targets, bringing people in on foundational level roles. We've done a skills boot camp, for example, where we had the opportunity to bring in 20 people who are currently unemployed, put them through a week of training on things like health and safety, site management. Then the second week, they had the opportunity to get a [certification] ticket for a roller or a front-loading dumper, which provides them with a skill that they can then take away from the project and use in the wider local area with all the other construction projects going on. We can bring people in, give them foundational skills and then build upon them for the next four years, train them up into things like excavators and dozers so they can go on and work in the sector and work on other reservoirs in the future.

NR: Bob, what are your reflections on how this new reservoir fits into the wider resource challenges that we've got in the UK?

Bob Taylor: The issue here is that we haven't really been in the habit of building reservoirs in this country and reservoirs are critically important, perhaps even more so nowadays than in the past, because our water infrastructure is designed around the weather and the climate. In simple terms, we need reservoirs to store water when we have lots of rain in the autumn, which refills our aquifers under the ground and increases the flows in all of our rivers. We can take water out of those rivers and put them into reservoirs for when we need that water in the summer, when temperatures are higher, demand is higher and there is less rainfall.

The fact that we haven't had the resilience of reservoirs to call on as much over the last 30 years is now recognized as a major issue, and that's why this is the first of 10 new reservoirs that we're planning over the next 20 years or so around the UK. If you look at the holistic picture of all of this, we're building a water grid in the southern half of England so that we can move water from Wales, from the north west, from other parts of the UK, where we do have much more rainfall, to areas where water is much more scarce, in the South East and East Anglia.

NR: What about water reuse?

BT: It's a Southern Water proposal to put water from their largest wastewater treatment plant, Budds Farm, through as a state-of-the-art tertiary treatment system. So rather than discharging that water into the sea as normal through the conventional two-stage treatment process, you add a tertiary process on the end, to then put that water back into the reservoir and use for the potable water cycle. It's quite a new idea in the UK, but I've worked big chunks of my career overseas, where it's much more commonplace, in places like Spain, Singapore, America. The quality of the water that will come out of that tertiary treatment plant is actually better quality than the spring water, which is the kind of original source of water for Havant Thicket reservoir. Southern are trying to solve a [projected] 200 million litre-a-day [shortfall] in Hampshire. (To put that into context, that is more water than Portsmouth Water supplies in total.)

They're trying to find a lot of alternative sources for water in an area where we are already stressed, and adding the recycled water to the spring water for the reservoir will change the solution from being 10 per cent of what they need to 50 or 60 per cent of what they need. So it makes much better use of the reservoir asset and the infrastructure around it in terms of solving the problem for Hampshire. We need to take less water from those two iconic chalk streams, the Test and the Itching: they've been over abstracted historically, and there's a strong recognition that we need to restore the natural environment and those important natural habitats. These arrangements are designed to compensate for that.

NR: Are there lessons here for other reservoir projects?

BT: It hasn't been all that easy to source expertise in the UK, because we haven't built reservoirs for a long time. We use a lot of internationally backed businesses to help us with this. But there's a whole industry ahead. Reservoirs are hugely interesting structures for people. We've had a massive response from people who want to visit the site and have a look at what's going on and people are truly gobsmacked when they see what we're planning to do.

And if you compare it with, for example, the scale of the reservoir that Thames Water wants to build near Oxford, ours is a bit of a puddle. It's generating a lot of interest because of all of the things that people get confused about around our industry and how it works, the fact that this is the first reservoir for 30 years is something that everybody understands.

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There’s much more where that came from – listen to the full conversation here. You can search for Planet Possible in your favourite podcast app.

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