A water company has unveiled a £1.5 billion plan to cut the number of storm overflow spills by 8,000 a year.

Southern Water has set out its Clean Rivers and Seas Plan which aims to reduce spills through a combination of nature based solutions, including rain gardens, tree planting and installing water butts to slow the volume of rainwater going into the combined sewer and by increasing the capacity of the network.

In stormy weather, rain can overwhelm combined sewer and drainage systems which exist across Sussex.

Southern Water said that in these circumstances it releases storm overflows “to protect homes, schools and businesses from flooding”.

The company, which was recently revealed as one of the most complained about, said phase one of the plan will be delivered between 2025 and 2030 and will see an investment of £700 million to focus on areas such as shellfish and bathing waters, and environmentally sensitive sites.  

By 2030, it said 50 per cent of high priority overflows will meet government targets, reducing spills by 3,000 a year.   

By 2035, 75 per cent of high priority overflows will meet government targets, reducing spills by 8,000 a year, bosses said. 

“We understand our customers want to see change now,” a spokesman from the company said.

“We face tough choices in striking a balance between environmental protection and minimising the impact on bills for customers.

“Although customers will notice the impact reflected in their bills, the average water bill is one of the lowest household bills. Some of the work will take a long time, but we are committed to investing the time and expertise to go as quickly as possible.

“This is why we are asking our customers for their feedback on our Clean Rivers and Seas Plan via so they can tell us if they agree with how we are prioritising overflows in our region before we agree it with Ofwat, our regulator.”

Southern Water had to hand back over £40 million to customers after it failed to meet targets set by watchdog Ofwat.

It was revealed that the company spilt sewage into the county's waterways illegally on dry days 60 times last year.

And a report in July showed that the company was in billions of pounds' worth of debt.

CEO of Southern Water, Lawrence Gosden, said: “I’ve heard our customers’ concerns, and we take our impact on the environment seriously. We have a long-term strategy to 2050 that will restore and protect our regions’ rivers and coastal habitats and a large part of that will be to get to the root cause of storm overflows. 

“We cannot simply switch storm overflows off. But by implementing this Clean Rivers and Seas Plan and tackling the root cause, slowing the flow of rainwater going into the combined sewer, while increasing capacity of our network, we can reduce their use.

“Collaboration is key, and we cannot achieve the results needed alone. That is why we are calling on our customers and local authorities to work with us and adopt solutions like water butts or sustainable drainage systems, to channel rainwater safely and slowly back into the environment.

“Together, we can go faster and further, protecting our communities and our environment.”