The sewer system
Here you can find out about the UK sewer system, its history, the growing challenges our network faces how we're responding in the South East. We're also look into sewer sealing and the innovative techniques we're using to upgrade our sewers.
Combined sewers
The combined sewer system was built by the Victorians in the late 1800s. A network that now stretches over 40,000km in our region alone, working hard to take wastewater away from homes and businesses.
During heavy rain, once the ground has absorbed all it can, any extra water starts to squeeze its way into the network and as a result the system becomes overwhelmed, leading to flooding and storm overflow releases.
Everything you need to know about sewers
What we’re doing
From our Pathfinder projects used to slow the flow of water to expanding our treatment works and using AI to find and fix leaks, we’re working hard to relieve the pressure on our network.
One way we’re doing this is sealing sewers. By reinforcing the pipes we can stop groundwater from finding its way in and overwhelming the system. We’re rolling out this method in areas that have been impacted by high groundwater levels and frequent flooding.
Challenges we face
Our sewer system is under more pressure than ever because of the growing population and unpredictable weather. It’s important we find a way to keep all the extra rainwater out of our sewers to future proof the network.
Digging up and replacing all 40,000km of network would cause a lot of disruption to our communities. Instead, we’re using innovative technology to seal sewers, helping to reduce storm overflows and prevent future flooding caused by heavy rainfall.
A brief history
The first sewer systems were built by the Indus Valley Civilisation around 3000-2000 BC and laid the groundwork for modern sanitation.
During the 19th century, the UK developed its extensive underground sewer network, including thousands of miles of combined sewer. These types of sewers carried wastewater from homes and businesses, along with rainwater runoff, directly out to rivers or beaches.
Over the past two centuries, improvements in sanitation and environmental protection have positively changed the network with more extensive sewer treatment and regulations.
Sewer sealing
Watch this short video below to learn more about our sewer sealing projects.
Sewer sealing involves inserting a resin-coated tube into an existing pipe. It is then inflated and cured in place with UV light, creating a strong, seamless lining.
Another method uses TuboGel, a special gel made up of two liquids flushed through the pipes. The first leaves a coating on the inside and the second causes a chemical reaction to solidify the coating.
As well as re-lining sewers, sewer sealing can also involve patching small sections of pipework only where it's needed. These technique reinforces ageing or damaged pipes without needing to dig up the roads.
In 2022 more than 30 tankers per day were needed in Pan Parishes to remove excess groundwater from the sewer and transport it to one of our wastewater treatment works. We’ve recently sealed over 4.5 kilometres of public and private pipework in the area, completely eliminating the need for tankers in the area.
We’re rolling out this method in areas that have been impacted by high groundwater levels and frequent flooding.
Much of the ground in our region is made up of chalk which acts like a sponge soaking up excess rainwater until it becomes saturated. When the ground can’t absorb any more water, it comes up through drains and gaps in the ground leading to groundwater flooding with a huge impact to local communities.
