Causes of sewer flooding

Some of the common causes of sewer flooding, include blockages, damaged pipes and heavy rainfall.


Blocked drains and sewers are often the cause of sewer flooding, and we deal with around 13,000 blockages on our network every day.

Most blockages can easily be avoided by disposing of wet wipes, sanitary items and fats, oils and grease (FOGs) correctly.

Learn more about how to avoid blockages.

Heavy rainfall

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.

Find out how to help manage rainwater runoff.

Damaged pipes

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.