Storm overflow investment

What are these solutions? 

We can’t just remove storm overflows from our network as this would cause a flooding risk (and we’d need to find somewhere for all the rainwater to go). That’s why we’re looking at reducing the number of times they’re needed by deploying these innovative and resilient engineering solutions:

• surface water sewers to separate out rainwater and divert it to the nearest watercourse
• underground storage tanks to hold the stormwater
• nature-based solutions
• sustainable drainage system

Surface water sewers

Surface water sewers divert rainwater into a dedicated sewer which is separate to the combined sewer to reduce strain on the sewer network. This helps prevent the wastewater network from becoming overwhelmed during periods of bad weather and means that rainwater can be redirected back into waterways without having to go through our wastewater treatment process. 

Underground storage tanks

Storage tanks can store excess wastewater, meaning when there’s heavy rainfall, we’ll be able to hold more excess wastewater back and reduce reliance on storm overflows during periods of bad weather. 

Nature based solutions

Nature based solutions include full treatment and phosphorous-specific wetlands. 

These wetlands are made up from a number of interconnected ponds filled with a variety of wetland plants that naturally treat wastewater by removing pollutants. Phosphorus wetlands go a step further, using specific plants that can absorb and break down phosphorus, helping to filter wastewater in a sustainable and low-carbon way while also providing a habitat for wildlife to thrive. 
Once the water is treated it drains back into a local watercourse, removing excess strain from the sewer network.

Sustainable drainage systems

Sustainable drainage systems include permeable flooring, swales and rain gardens.

These sustainable drainage systems help slow the flow of rainwater in built-up areas where concrete and tarmac dominate. Because these hard surfaces don’t absorb water, rain runs off into drains, which can put extra pressure on the sewer network. These sustainable drainage system solutions ease that strain by capturing rainwater in a more natural, sustainable, and low-carbon way.

Here's a list of some of the projects coming up next: