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Explains
The scale of the challenge
“Drought is not new in the UK, but in terms of water scarcity, it needs to be taken very seriously,” Graham Bateman, technical director for water at GHD, tells Utility Week Intelligence. We caught up with Bateman in mid-August. “We’re seeing the scale of the challenge right now. All of Wales is in drought, as is 70% of England, and July was the driest since records began. It’s a wake-up call for everyone.
“The impact is clearly being felt by customers but also across the environment. Farmers and wildlife are being affected, and we’re seeing a proliferation of wildfires. Hosepipe bans and other temporary use restrictions are already in place.”
Southern Water applying to DEFRA for stricter restrictions on non-essential water use is unusual, he adds. “These are relatively rare measures, affecting activities such as swimming pools, leisure centres and car washes. Not all these applications will be granted, but they are a barometer of where we are in terms of water stress.
“They really underline the seriousness of the situation.”
The scale of the challenge
“Drought is not new in the UK, but in terms of water scarcity, it needs to be taken very seriously,” Graham Bateman, technical director for water at GHD, tells Utility Week Intelligence. We caught up with Bateman in mid-August. “We’re seeing the scale of the challenge right now. All of Wales is in drought, as is 70% of England, and July was the driest since records began. It’s a wake-up call for everyone.
“The impact is clearly being felt by customers but also across the environment. Farmers and wildlife are being affected, and we’re seeing a proliferation of wildfires. Hosepipe bans and other temporary use restrictions are already in place.”
Southern Water applying to DEFRA for stricter restrictions on non-essential water use is unusual, he adds. “These are relatively rare measures, affecting activities such as swimming pools, leisure centres and car washes. Not all these applications will be granted, but they are a barometer of where we are in terms of water stress.
“They really underline the seriousness of the situation.”
This year saw the driest July ever recorded, leaving 70% of the UK in drought
This year saw the driest July ever recorded, leaving 70% of the UK in drought
Is a severe water crisis on the horizon?
The drought conditions experienced in 2026 may just be the start. The government warned last year that England could face a five billion-litre-a-day shortfall in public water supplies by 2055 – around a third of today’s daily use. That’s the equivalent of 2,000 Olympic-sized swimming pools. A further one billion litres a day may be needed for energy, food production and emerging industries.
The Environment Agency says 60% of the gap must come from reducing demand, particularly cutting leaks and improving efficiency (which is why the water smart meter programme and maintenance and replacement of networks are so vital). Forty per cent will require new supply infrastructure.
One of these supply projects is underway. It’s the construction of a new reservoir at Havant Thicket designed to strengthen water security while protecting vulnerable chalk streams. Havant Thicket is the first major new reservoir to be built in the UK for more than 30 years. A joint venture between Portsmouth Water and Southern Water, it will help reduce Southern Water’s reliance on the River Test and River Itchen, two of England’s priceless chalk streams.
The Test and Itchen are rare habitats. In fact, they are among only approximately 200 chalk streams globally. Fed by naturally filtered groundwater from chalk aquifers, these rivers feature cool, clean, mineral-rich water and steady flows. This helps make them ideal conditions for wildlife including endangered chalk-stream salmon. The Test and Itchen, however, are increasingly threatened by over-abstraction and pollution from sewage and chemicals. Even relatively small reductions in river flow can make conditions difficult for salmon and other aquatic life.
A reservoir fed by spring water
That’s where Havant Thicket comes in. The reservoir will be swelled by the natural springs that already provide around 30% of Portsmouth Water’s supply. During wet periods, surplus spring water currently flows out to sea. The reservoir will capture and store this excess water for use when demand is higher. “Portsmouth Water will then supply the stored water to Southern Water, helping maintain supplies while reducing pressure on the sensitive chalk stream,” explains John Hensman, a GHD Principal and UK water market leader. He points out that the land for the scheme was secured as far back as 1965, illustrating how long new reservoirs can take to come to fruition.
(The project is billed as an environmentally led solution to a growing regional water-security challenge – making better use of existing natural resources rather than relying solely on increased abstraction. It’s also a great example of water companies working together to serve customers in different areas.)
Work is well underway on Havant Thicket, plans for which were set out in Portsmouth Water’s water resource management plan (WRMP19) – but first identified in Portsmouth Water's WRMP09 planning process in 2008. The reservoir is forecast to be completed in 2030 and to supply an expected 21 million litres a day. It is just one of 10 new reservoirs proposed by water companies, each with a daily supply in excess of 10 million litres a day by 2050 [see table below].
The largest of these, the South East Strategic Resource Option (now known as White Horse Reservoir), will provide water to Thames Water, Affinity Water and Southern Water customers.
Source: Environment Agency
Havant Thicket should be used to inform development of these other projects, Hensman says. “There are a number of programmes, and future projects can learn from lessons we and others have taken from Havant Thicket, particularly around the benefits of early collaboration.” This includes using digital tools to support delivery, how to engage with stakeholders, and how to integrate environmental objectives into the design process from the outset.
“From our perspective, the project has also demonstrated the value of bringing together global experience and local knowledge. We’ve had a strong reservoir team in Australia supporting the project and helping us solve some of the challenges we’ve faced.” This included bringing in an Australian dam and reservoir engineering specialist with deep expertise in dam safety, embankment dam engineering and reservoir infrastructure -– expertise that can be hard to find on these shores.
For GHD, being able to draw on this experience is important. Havant Thicket has been technically complex from an engineering standpoint. For example, the ground conditions have been particularly challenging. “It’s a reservoir project, so there are major earthworks, as well as critical structures to design,” says Hensman. “The reservoir culvert has been interesting, as have the valve tower and spillway — these are structures that haven’t been designed at this scale for a while in the UK.”
Another particularly important consideration is how to mix water from Southern Water’s proposed Hampshire Water Transfer and Water Recycling Project with local sources. Recycled water from the Southern Water scheme, due to commence in 2029, will eventually be pumped into the reservoir, where it must mix correctly with water from the springs flowing into Havant Thicket.
“Ensuring that the water mixes effectively and that water quality is maintained is a critical part of making the whole system work,” explains Hensman.
“The project has also demonstrated the value of bringing together global experience and local knowledge.”
John Hensman, UK water market leader, GHD
