Southern Water: The long road back

Flooding, Management & Regulation, Natural Environment, Processed Water

After record fines and public backlash, Southern Water is aiming to make strong progress on tackling its storm overflows, informed by a range of pilot projects.


Of all England’s water companies, Southern Water has arguably faced the most acute backlash from campaigners on its sewage discharges. The company has roughly 1000 of the UK’s 15,000 or so storm overflows, plenty of coastline and a sizeable population.

In 2019 it was fined £126m by Ofwat for historic “serious failures” in operation of its sewage treatment works and misreporting of these. It still faces considerable challenges with the frequency of its storm overflow discharges but previous Chief Executive Ian McAulay was determined to turn around Southern’s environmental performance and begin the slow process of rebuilding customer trust through transparency.

This approach continues to put Southern in the firing line of campaigners. Its Beachbouy reporting platform provides the public with near real-time information on the release of stormwater. Ammunition to be fired straight back through social and mainstream media – a painful but necessary lancing of the boil.

Added to this its self-reporting under the environmental performance assessment (EPA) is high – partly why the company’s pollution performance is worse than many others.

Southern know – like all other water companies – that making inroads into pollution from storm overflows isn’t going to be quick given the number of problem overflows and sewer catchments that will need to be investigated and remediated.

In the summer, government published its storm overflows discharge reduction plan. The £56 billion programme between now and 2050 isn’t ambitious enough for some – including many Southern customers.

On his first day in the role, new Secretary of State for Environment, Food and Rural Affairs Ranil Jayawardina told water company bosses they had two weeks to send him their plans for how they were going to make “significant improvements”.

But Southern are determined to outperform. Not only that they want to do it in a way which builds their green credentials and grows the trust of their customer base. That means wherever possible, doing it through blue-green infrastructure and other distributed means which customers can see and feel, and which deliver wider benefits. Sustainable drainage systems (SuDS), water butts and more alongside sewer rehabilitation and network optimization are likely to feature heavily.

So what will these plans look like? To inform theirs, Southern have created their own regional taskforce (different to the government-convened Storm Overflows Taskforce) to analyse and learn from five pilot projects which are running in catchments of differing characteristics. This will form a regional storm overflows plan which will feed into the next PR24 business planning round.

Central to these pilots is an enhanced approach to complaints handling and service. The aim is to turn repeat complainants into advocates – supporting a much larger communication and outreach campaign.

The public’s understanding of sewerage and storm overflows has understandably been light until the issue exploded into the media spotlight. Whereas once the mentality inside companies may have been to be a ‘silent service’, now thinking is to increase understanding of the whys and wherefores of combined sewers and the trade-offs that will always be involved.

The potential of the Beachbouy app hasn’t yet been fully tapped and offers the ability to act as a platform for awareness on behaviours (on use of unflushables and impermeable surfaces for example) as well as presenting other publicly available and relevant data to provide local context to spills when they happen.

In Deal, the first of the pilot areas, surface water flooding is a major issue due to the local topography and its interaction with highways, the amount of impermeable surface in the area and how sewage is pumped in the network. Here, removing surface water from the combined network is a major focus.

A four-street experiment in the area is looking at a range of different combinations of SuDS approaches with one street acting as a control. Collaboration with community engagement body Groundwork and landscape architects is resulting in high interest.

Margate – the second area – is a large, classic combined sewer catchment. The irony is that it is built on well-draining chalk next to the sea. If there was ever a place where surface water didn’t need to go into combined sewers this would be it.

Collaboration has been a key part of the work here so far. Kent County Council already has public green spaces with large SuDS features in them and are keen to collaborate. This is identifying wider opportunities such as the restoration of a unique fountain (the only other one of its kind is in the Raffles Hotel in Singapore) within blue green infrastructure in a public park. Southern are finding that conversations around different peoples’ needs helps to unlock sometimes unforeseen doors. This needs a very different approach to the conventional totex hierarchy so often applied to investments.

In Swalecliffe – the final pilot in Kent – there is actually a lot of separated sewer systems but yet the area suffers from frequent overflow spills. An underlying reason is that a lot of the separate networks ultimately connect into combined systems. These connections need to be reviewed and potentially re-engineered as was done in Portsmouth a decade ago. Added to this there is considerable scope for SuDS retrofit to ease the pressure on the combined network.

Two other pilots offer very differing sets of circumstances. On the Isle of Wight, project Seaclean Wight in the 1990s pumped all sewage on the island to Sandown sewage works for treatment. However, a large, complicated sewer network with extensive pumping allied to large impermeable areas mean overflows are spilling above average despite meeting permit conditions. Here, network optimization offers great potential to make inroads on the issue, whilst SuDS and widespread installation of leaky water butts for residents will help ameliorate the impact of the impermeable surface.

The final pilot – the ‘pan-parish’ approach near Andover – is looking at a different challenge. Here overflows are spilling into a chalk stream that is a tributary of the River Test. Groundwater ingress into combined sewers is the big challenge. Whilst sewer re-lining using silica-based gels is yielding some wins, in places there is over 1 bar of groundwater pressure flowing into the sewers. Here, Southern think that the ultimate solution will be wetland treatment areas by the overflow outfalls.

Other approaches across the pilots are SuDS for schools – with more than 40 schools engaged in retrofit schemes. And, concerted engagement with highways authorities is should also help to eat into the amount of highway runoff in combined networks – half of the volume in some of Southern’s sewer catchments.

Right now, the pilots will be starting to kick out data and lessons which can help Southern refine its plans and approaches for incorporation into PR24. Its aim is to be able to deliver schemes of comparable size to the large SuDS retrofit scheme being delivered under green recovery funding by Severn Trent in Mansfield – but all being well cheaper.

Ultimately, Southern’s storm overflows lead Nick Mills feels that this is all pointing towards a new dawn for integrated water management. But one area of need he sees is a coordinator and appropriate duties for the various players within the system.

There are many different parties involved, all with a stake: local authorities, internal drainage boards, the Environment Agency, property developers, water companies and more. Mills points to the USA – which he says had its “storm overflows moment” some years ago now and has put in place legal duties and powers to direct these parties to prioritise collaborative working and pool resources.

This may need to come and perhaps will in time. In the meantime the priority is on building up the understanding of root causes, analysing data and monitoring performance (through University of Exeter). Southern are committed to sharing their learning, providing GIS layers to local councils and highways authorities to optimize wider activities like traffic calming and street tree provision.

The aim: collaboration, transparency, rebuilding community and customer trust and, out-performing the Defra targets.

Share this article

Become a member

Whether you are studying, actively looking to progress your career, or already extensively experienced, our membership will add value and recognition to your achievements. We can actively help you progress throughout your career.

Become a member

View our events

We organise a wide portfolio of UK and international thought leading events, providing an industry recognised forum for debate, CPD and sector networking. These events also support our policy work and inform key initiatives.

View our events