South West Water Highlights Flash Flooding Risks During Flood Action Week

South West Water is marking Flood Action Week by raising awareness about the dangers of flash flooding and sharing how it’s working to protect communities across the region.

What Causes Flash Flooding?

Overland flash flooding happens when heavy rain falls in a short space of time, often taking people by surprise. It can occur at any time of year and can be especially dangerous after long, dry spells.

Prolonged warm weather hardens the soil, preventing it from absorbing rainwater. Instead, the rain runs off into surface water drains, which can overwhelm the sewage network in areas with combined sewer systems.

Flash floods can also strike during wetter months when already saturated ground struggles to absorb more water, again increasing the risk of flooding.

The Met Office reports that as the atmosphere warms, it can hold more moisture, leading to more intense and frequent downpours.

How South West Water Is Helping

Although surface water drains are not owned or managed by South West Water, the company says that on combined systems, intense rainfall can overwhelm sewer networks. It remains committed to reducing and resolving flooding from sewers, which often interact with other types of flooding.

The company is taking several measures to help reduce the impact of flooding on customers:

• Surveying likely flood areas: Regular surveys, local input and collaboration with councils help identify and mitigate risks in high-risk areas.

• Monitoring weather patterns: Keeping ahead of forecasts allows extra teams to be deployed to support communities during potential floods.

• Reducing rainwater in wastewater systems: Disconnecting non-absorbent areas and creating natural drainage features like ponds or ditches helps prevent network overload.

• Planting trees and restoring peatlands: Through its Upstream Thinking catchment management programme, South West Water helps the land absorb more water, reducing flood risk.

• Deep cleaning sewers and tanks: Regular maintenance prevents blockages that could otherwise lead to flooding.

• Improving rural infrastructure: Enhancements in rural drainage systems help ensure less field run-off enters the network.

South West Water’s Head of Tactical Asset Management, Hazel Tranchant, said:

“Predicting when flooding will occur, and what impact it will have, can be difficult as it is a complex phenomenon affected by multiple variables – such as where rain falls, for how long, and how saturated the land is.

“Although the effects of overland flash flooding aren’t our responsibility, we’re working hard behind the scenes to keep sewers in great condition to reduce and prevent flooding from our sewers during heavy rain.

“We work closely with local councils on practical solutions to flooding to help protect communities.”

What You Can Do to Help

Customers can also play their part in preventing blockages and flooding by only flushing the 3Ps – pee, poo and paper – and avoiding pouring fats, oils or grease down sinks.

About Flood Action Week

Flood Action Week is an annual campaign launched by the Environment Agency to raise awareness about flood risks and how to prepare for them.