RBWM must 'get it right' when managing flood risk of the future

RBWM must ‘get it right’ when agreeing a new strategy to deal with flooding, councillors have said – especially as the borough is facing considerable development.

Every year, RBWM is faced with flooding in multiple places. As such, it needs a flood risk strategy to manage it, including marking places of priority for specific flood risk schemes.

The current strategy was published in 2014 and a new one is necessary. Now this is in the pipeline, spanning from 2026 to 2041.

It sets out objectives around maintaining council-owned assets, managing watercourses and being adaptable to the changing climate.

RBWM will need to plan for around 20,000 new homes across a 20-year period and must think about drainage carefully.

As such, the draft was presented to councillors for their consideration at a place overview and scrutiny panel meeting on Monday (March 9).

Councillor Gary Reeves (Lib Dem, Cox Green) commented on the level of future development planned for the borough, saying: “That’s going to have a huge impact in a flood risk area.

“It’s very important that we get this right, because we don’t get a second chance in these big developments.”

He added that there are ‘concerns’ over Thames Water’s ability to provide the appropriate drainage.

The water company is responsible for managing the risk of flooding from sewers, including surface and foul water.

Ben Crampin, RBWM’s principal flood risk manager, stressed that it is the council’s responsibility to check whether drainage strategies developers put forward are up to standard.

That is important, because there are limited chances to impose any obligations on companies.

“If a Thames Water sewer is blocked, we have no ability to enforce that work,” he said. “Likewise, we have no ability to enforce any improvement works [that need] to be made.”

Planning authorities use flooding data when assessing applications in areas that may be at risk of flooding.

A ‘major concern’ is the need for up-to-date data to be provided to councillors, Cllr Reeves added – as it is important this is correct before it is used for planning purposes.

Mr Crampin said the most recent update was provided by the Environment Agency in 2025.

It provided updated information on surface water flooding and watercourse flooding, using newer rainfall projections and terrain data.

Flood mitigation schemes are prioritised using scoring systems – based on the number of properties affected, the severity of flooding, or the economic damage.

Highway drainage works, for example, are prioritised partly on safety factors such as proximity to a school or the speed of the road.

The higher the road’s speed, the greater the risk, increasing its prioritisation for a flood risk scheme.

In addition, councillors sometimes raise specific sites because residents have complained about repeated flooding, blocked drains or problems that may not show strongly in the data.

This is described as a ‘political interest’. Although it brings in fewer ‘points’ in favour of prioritising a flood risk scheme there, it is still a consideration.

Mr Crampin said: “It’s useful for us to have as much data reported to us as possible.

“If residents are aware of flooding issues in their area, the more information we have from them the better.”

The draft strategy is expected to be discussed at a cabinet meeting in April or May, followed by a six-week public consultation.