Southern Water

What the Conservatives are doing to improve the quality of our rivers, beaches and seas.

In brief.


  • The 2021 Environment Act mandated the biggest overhaul of the wastewater system since the Victorian era. Water companies will be required to invest over £56 billion to dramatically improve water quality. This will be the biggest environmental investment programme in their history.
  • Water quality in the UK has slowly been improving since the 1970s, when many rivers in England and Wales were considered biologically dead.

On the Island:

  • Working with others, I persuaded Southern Water to make the Island an example of national best practice for reducing storm overflows and cleaning up our environment. This means the Island has been amongst the first to trial solutions such as water butts and sustainable drainage systems.
  • Southern Water have allocated £230 million to the Island’s sewage network. This is the equivalent of over £3,500 invested per household on the Isle of Wight. This includes:
    • 11,000 more water butts
    • 9,000 sustainable drainage systems
    • Improvements to 550 driveways
    • 3,100 sustainable roadside rain gardens.
  • For a full list of proposed investments, please go to:


In the next two decades, the water utility firms will be investing £56 billion to dramatically improve the cleanliness of our rivers, beaches and seas. Specifically, they are being told to deal with the issue of storm overflows.

What’s the problem and what are storm overflows?

Pollution into UK rivers and beaches damages wildlife and is unpleasant and sometimes unsafe for humans. It comes in different guises. Much pollution is caused by agricultural run-off. Another form of pollution is caused by storm overflows. This is when stormwater overwhelms the drainage system and on occasion takes raw human sewage with it into rivers and seas.

Under previous governments the problem wasn’t properly monitored, so we didn’t know how bad it was, although we knew it was bad. So bad indeed that the last Labour Government was taken to court by the European Union.

According to the Environment Agency, storm overflows are:

“a result of Victorian sewer infrastructure, operating as safety valves built into the combined sewer system. They discharge excess sewage and rainwater to rivers, lakes, or the sea when the sewer system is under strain. This protects properties from flooding and prevents sewage backing up into streets and homes during heavy storm events. A growing population, an increase in impermeable surfaces and more frequent and heavier storms because of climate change have increased pressure on the system.

There are around 15,000 storm overflows in England. They discharge at different rates depending on local conditions including climate, rainfall and the type of sewerage system. In 2021, 90% of storm overflows discharged at least once, with 5% discharging more than 100 times, including in high priority nature sites such as Sites of Special Scientific Interest. Bathers and other water users are impacted by the 8% of storm overflows that discharge near a designated bathing water. 

High levels of sewage discharges present two main types of harm: 

Harm to public health 

Discharges from storm overflows contain raw sewage, which can contain high levels of harmful pathogens, such as viruses and bacteria. This can pose health risks to people who use our water bodies for recreation. 

Harm to the environment 

Storm overflows can also lead to ecological harm due to their impact on water chemistry. Discharges of raw sewage can contain organic pollutants, microplastics, pharmaceuticals, nutrients, and heavy metals, as well as visible litter that is flushed down toilets. The impact of sewage discharges on ecology varies depending on the pollutants it carries, their concentration, and the nature of the receiving water body. The smaller and more dilute the sewage discharge, and the larger and faster flowing the receiving river, the lower the ecological impact.”

Why is this investment happening now?

In 2021, the Government brought in the Environment Act, enforcing much higher standards for environmental protection and higher standards for water firms. Specifically, there is also now a national plan for storm overflows into rivers, beaches and seas, and a national Integrated Plan for Water, announced April 2023, to clean up water supply for future generations.

Details of all three are here:

There have been significant improvements in water quality in the past ten years. Despite storm discharges, UK bathing waters continue to improve. Last year, 93 percent were classified as ‘good’ or ‘excellent’, up from 76 percent in 2010. Supply interruptions to customers have decreased five-fold and leakage has been cut by a third since privatisation. Pollution in our rivers has significantly reduced. There is now 80 percent less phosphorus and 85 percent less ammonia compared to 1990, when water companies were privatised. Cadmium and mercury in the water environment have also reduced.

The Government’s plans will now make further progress.

Why have these changes not happened already?

In the past decade, water firms have been instructed to meet two key objectives: reducing leaks and ensuring the standard of drinking water. As to the first, water leakage had been an ongoing scandal due to the age of water infrastructure and a lack of investment when the water firms were publicly owned. Since then, some 40 percent of pipes in the UK have been replaced and UK tap water is among the cleanest in the world.

Under public ownership, the water firms invested about £500 million a year. Under private ownership that rate of investment doubled to £1 billion a year, and now, under the new Conservative plans, the rate of investment will double again.

Over the past few years, it became clear that the new focus for the next decade should be on significantly reducing the damage being done to our rivers, beaches and seas by storm overflows and other forms of pollution. This was led in Parliament by the Conservative Philip Dunne, MP for Ludlow, whose painstaking work on the Environmental Audit Committee showed the scale of the problem.

The Government have since brought in the ground-breaking Environment Act, accompanied by a plan for water and a plan for storm discharges. 

How did water firms perform under the previous Labour Government?

Disgracefully, water firms under the previous Labour Government were given permission by Labour to self-monitor. This represented a clear conflict of interest between the Labour Government and privatised utility firms that Labour MPs professed to dislike.

As my MP, what have you done about it?

Working with others, I persuaded Southern Water to make the Isle of Wight an example of best practice nationally. This means prioritising the Island both for funding and for projects to significantly reduce the amount of water entering the sewers during storms. 

In total, Southern Water will, on current figures, invest £230 million in the Island’s sewage network.

Millions of pounds have already been committed to schemes big and small, including £13.5 million for Sandown Water Works, £2.5 million for work at Knighton, £5 million for Carisbrooke and over £7 million for works in Cowes, Newport and Brading.

What is Southern Water’s pathfinder project?

The Isle of Wight is now one of a small number of Southern Water ‘pathfinder’ projects for reducing sewage discharges. The project involves an investment programme designed to significantly reduce sewage and storm overflows into rivers, beaches and seas around the Island.

The first trial of the pathfinder project, a project in Havenstreet, is now complete. Approximately two thirds of Southern Water customers in Havenstreet took part in the scheme. Before the trial, Havenstreet pumping station spilled 20-30 times per year. Southern Water has increased the pumping rate of Havenstreet pumping station; installed 147 slow-release water butts; and diverted the roof drainage of 5 large roofs into planters. The scheme has resulted in a 70 percent reduction in local storm overflow activity.

As part of Southern Water’s Clean Rivers and Seas Plan, Southern Water plan to invest £230 million in the Island’s sewage network to tackle storm overflows. This means installing 11,000 more water butts and 9,000 sustainable drainage systems; improving 550 driveways; and installing 3,100 sustainable roadside rain gardens.

Overall, Southern Water have committed to reduce spills by 49 percent in bathing water areas and 50 percent in shellfish areas by 2030.

Ongoing investment in water supply assets includes pump, tank and treatment improvements at Sandown Water Supply Works and a major programme of other water supply refurbishments. The wastewater treatment programme will see improvements to numerous wastewater treatment works to increase treatment capacity and prevent sewage discharges; increases in stormwater capacity at key treatment works; and other upgrades to reduce phosphorus discharges.

Furthermore, between 2025 and 2030, Southern Water has set out plans for a major water recycling project on the Island. This will allow the Island to recycle more of its own water supply and gain greater independence from the mainland UK. Planning submissions are set to be completed in January 2024. The treatment plant is forecasted to be operational by the end of 2026.

I will continue to work with community groups, councillors and Southern Water to make sure we maintain and improve our Island’s environment – this is all part of getting a better deal for the Island.