Some of the common causes of sewer flooding include blockages, heavy rainfall, groundwater infiltration and damaged pipes.
Learn about how they can cause sewer flooding, what we are doing to tackle them, and how you can help reduce their impact.
Blocked drains and sewers are often the cause of sewer flooding, and we deal with thousands of blockages on our network every year.
When a sewer is blocked, sewage cannot pass through the pipe as it usually would. This can then cause sewage to back up into bathrooms and kitchens.
Our sewers are designed to take sewage away from properties. In some cases, they also take away surface water which runs off roads, footpaths and paved areas.
Our sewerage system can cope with day-to-day flows, but exceptional wet weather can overwhelm it and cause sewer flooding.
Sometimes groundwater, held within rocks and soil, gets into drains and sewers. This is known as groundwater infiltration and normally happens during or after heavy or prolonged rainfall.
Most homes are connected to a public sewer in the road through private drains, which carry the foul water from baths, washing machines and toilets.
When groundwater is high, it can be forced into public sewers and private drains through small cracks in pipes or inspection chambers. Over time, these small flows can inundate sewers and cause flooding.
Watch this video to find out more about how groundwater causes sewer flooding.
Many of our sewers were built at the start of the last century or earlier and because the pipes are underground, it’s not always obvious when they are damaged.
They can be broken or damaged by tree roots or soil movement during very dry or winter weather, which can make sewer flooding more likely.