Sewerage network

We treat 480 million litres of sewage from 2.8 million customers every day.

We have:

Sewage flooding

Sewage flooding is rare but when it does occur it can be devastating so tackling it remains a key objective.

The number of sewer flooding incidents was 1.43 incidents per 10,000 properties in 2018-19 compared to our target of 1.68.

We were ahead of our target as a result of:

• our campaigns about the problems caused by flushing wet wipes down
  toilets and pouring fat down sinks
• optimising operational maintenance
• the generally dry weather conditions in the region last year.

We continue to work closely with the national 21st century drainage programme to try to bring about change in what customers flush into the
sewers because this factor has the biggest impact on flooding and pollution levels.

In 2015, we introduced a new and innovative measure of overall flood risk due to inadequate capacity of our sewers during heavy rainfall. Last year we invested £9m to reduce this risk at 87 locations and have met our target.

A large project at Brent Knoll was delivered in 2017-18, which reduced the risk of flooding to 46 locations.

The responsibility for flooding is complex and we work closely with other flood risk management authorities – we were consulted more than ever before, attending more than 120 liaison meetings. We contributed over £100k towards the partnership schemes to reduce flood risk, including £50k towards a scheme in Wrington, Somerset.

A new framework is being developed for all water companies to give visibility of long-term sewerage plans. It is an ambitious framework which we are embracing, requiring drainage and sewage management plans to be published by 2023.

Several locations in our region with water bearing chalk strata can be affected by high groundwater levels which infiltrate the sewer network and restrict toilet use. It is a complicated issue so to help customers understand it and help prevent it, we produced a computer-generated animation explaining ‘How groundwater can cause sewer flooding’.

Infiltration reduction plans

Our infiltration reduction plans continue to reduce the risk of groundwater entering sewers and drains. We proactively inspected more than 100 km of sewers for signs of infiltration and permanently sealed 6.1 km of sewers where seepage was occurring.