Sustainable drainage systems
Sustainable drainage systems (SuDs) use natural green spaces and eco-friendly solutions to soak up rainwater, taking pressure off the sewer network and preventing the use of storm overflows. Learn more about the different types of sustainable drainage systems and how you can install one.
Why do we need sustainable drainage systems?
When it rains, water from hard surfaces like roads runs off into nearby sewers, combining with wastewater. Although our combined sewers were designed to carry both surface water and wastewater from local homes and businesses, they weren’t designed to deal with the volumes of rain that we’re now getting because of climate change.
As more homes, roads and businesses have been built, there’s less land to soak up the rain and more water is running into the sewers which can overwhelm the sewer system. When this happens, storm overflows are used to prevent water backing up into homes and businesses or running down the street.
To prevent this, we’re putting in a series of sustainable drainage systems to soak up rainwater and stop it running into the sewers.
Different types of sustainable drainage systems
Slow-drain water butts
Slow-drain water butts collect rainwater to use on the garden or for washing your car. However, they also feature a drainage pipe halfway down, so the bottom half of the water is saved, and the top half trickles slowly back into the drain. This means there is always some space in the water butt to take more rain from the roof, preventing the sewer system becoming overwhelmed and causing storm overflows.
Raingarden planters
Planter boxes that sit underneath gutters to slow the flow of water coming out of them, preventing it from entering and overwhelming the sewage system. Think of it like a self-watering flower bed. Excess rainwater flows from the downpipe into the planter and is soaked up by the soil and plants.
Green spaces
Help water soak into the ground by planting grass, installing flower beds and creating raingardens, redirecting water that would normally flow into the sewers from hard surfaces such as paved gardens, car parks and playgrounds.
Rain gardens direct surface water into a specially planted area within to provide water for the plants and flowers there. This stops water flooding the area or overwhelming the sewer network.
Permeable paving
Permeable paving surfaces are made of either a porous material that enables storm water to flow through, or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can be
used for driveways, car parks, walkways and paths, playgrounds and more. With a 50m2 driveway creating half a tonne of water run-off when there's 10mm of rain, permeable paving can make a big difference.
Soakaways
Soakaways are cost effective and easy to create, and they’re completely invisible due to being hidden underground. Their construction involves digging a hole in the ground and stacking special crates or other permeable material in it. The material buried in the hole has plenty of empty space for water to enter and be stored so it can drain slowly and naturally back into the ground.
How else can you help?
We need landowner and local council permission to put sustainable drainage into place and so you can help by speaking up, encouraging local councillors and authorities to make these drainage solutions part of their plans.
You can also help by making sure your pipes are connected to the right sewer and where possible, allow us to separate your surface water from the combined sewer at no cost to yourself.
When building an extension, check that the water coming off the roof doesn’t connect directly to the sewer. Instead, use a drain chain into a flower bed.
Frequently asked questions
Your questions about sustainable drainage solutions answered.
Storm overflows are pressure release valves that open when there’s too much water in the sewer. If we reduce the amount of water entering the sewer, we reduce the pressure and a storm overflow is less likely to open.
Permeable pavements, swales (or shallow ditches in the ground), and retention ponds slow down and store excess water, allowing it to soak into the ground or evaporate.
They can be fitted on old roads as well as new ones.
While there is a cost attached to putting these solutions in place, they are low cost to maintain in the long term, and they help to increase local biodiversity, enhance air quality, and help to keep spaces cool during hot weather. These solutions can also be put in place without causing any major disruption to local roads, traffic, etc.
These are slow drain solutions and actually prevent standing water.