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Why a holistic approach is needed to reduce storm overflows

20 July 2023

Nick Mills explains Southern Water’s plan to create a more sustainable future.

Why a holistic approach is needed to reduce storm overflows
We all need to work together to engineer new solutions and change the way we think about water. Image credit: Shutterstock

It’s not a water crisis, it’s a water management crisis. Storm overflow releases are a national issue requiring urgent, collaborative action.

The answer sits with all of us – water companies, councils, property owners, supply chains, partner organisations and the public.

Together we need to revamp traditional ways of thinking to create a more sustainable future, going beyond end-of-pipe solutions towards a far more holistic approach.

In 2021, Southern Water set up the Clean Rivers and Seas Task Force, a dedicated team focused on reducing the use of storm overflows and preventing flooding.

The company also plans to invest £2bn into improving assets and environmental performance in England by 2025.

The government, meanwhile, has set up a Storm Overflows Taskforce and announced a programme of up to £56bn in capital investment – the largest infrastructure programme in water company history.

There is industry-wide momentum for reducing storm overflows.

The scale of the challenge

There are nearly 15,000 storm overflows in England. About 1,000 of these are managed by Southern Water, and in 2022 they activated more than 17,000 times.

These figures need to be vastly improved.

Legacy infrastructure manages both wastewater from homes and businesses and rainwater runoff from roofs and hard surfaces. This is only getting worse with the impact of climate change and the expansion of impermeable land in communities.

There is mounting pressure on water companies, engineers and the entire supply chain to understand, design and deliver interventions that will significantly reduce the use of storm overflows.

The water sector consists of a diverse system of interconnected assets. While some are owned by water companies and some are public, a large amount is privately owned.

While managing overflows remains critical, the water industry needs to combat flooding, reduce leaks and secure future supplies of clean water as part of improvement plans for the overall system.

Why collaboration is crucial

The decisions we make together are vital not only to reduce the impact of storm overflows but also to address wider environmental concerns and traditional landownership challenges.

The sector needs to pioneer a more holistic approach that aims to manage the sources of excess water into the sewerage system and prioritise the optimisation of existing systems ahead of building new assets.

Engineers, scientists, hydrologists, local authorities, project managers and community groups will all need to embrace a new approach to design and delivery.

As industry professionals, the responsibility sits with all of us to share our lessons and successes with each other and the public.

The public plays a critical part in overcoming these challenges.

At a time when wider society is at its most engaged, we must use this passion to drive the change that is needed to reform how we think nationally about water.

Where do we start?

The Clean Rivers and Seas Task Force has designed six Pathfinder projects to deliver improvements to assets that are both publicly and privately owned, installing sustainable drainage systems (SuDS) and taking a catchment approach to focus interventions.

This trial-based process allows Southern Water to assess the effectiveness and value of solutions in creating a sustainable network, enhancing industry knowledge ahead of the next asset management period, which starts in 2025.

rainwater planter for SuDs at schoolSouthern Water has installed raingarden planters at dozens of schools. Image credit: Southern Water

Good progress is being made.

The company has:

  • Published six Pathfinder technical reports and delivered on schemes.
  • Established strong stakeholder and community partnerships, including with local MPs, local authorities and design experts.
  • Undertaken 38 sustainable highway drainage schemes.
  • Optimised assets by increasing surface water pipes, digitalising pumping stations and building a small pumping station at Fairlee on the Isle of Wight, which is expected will reduce annual storm overflow releases by 95% in that location.
  • Installed raingarden planters at 43 schools, with another 50 planned this year.
  • Installed more than 1,000 slow-drain water butts at domestic properties – in Havenstreet on the Isle of Wight, this reduced the local storm overflow by 70%.
  • Resealed more than 100 private laterals contributing to groundwater infiltration.
  • Worked with more than 80 organisations with the biggest roofs/hard standing land, to install SuDS or separate their surface water from the network.
  • Worked with the Environment Agency to fix eight surface water misconnections and explore a further 32.

Such efforts have earned Southern Water nominations for the Water Industry Awards 2023’s Asset Management Initiative of the Year and Groundbreaker awards.

Collecting data has a huge role to play in reforming the company’s engineering approach and allowing it to consider new ideas.

One good example is the data gained from the recently installed event duration monitors that feed Southern Water’s Beachbuoy web app to provide near real-time storm overflow data.

This allows the public to check if there have been any releases in their area before they head to the beach.

Collaboration, transparency and a whole-system approach is the route to success.

There are plenty of case studies and early successes to share, but the fundamentals are clear – we all need to work together to engineer new solutions and change the way we think about water if we are to create a more sustainable future.

Sign up

Register here for the ICE Autumn Prestige James Forrest Lecture taking place on 5 September, where Nick Mills will deliver a keynote address on how engineers can drastically reduce storm overflow into rivers and seas now and over the coming decade.

  • Dr Nick Mills, head of the clean rivers and seas task force at Southern Water