Surface Water is the UK’s Biggest Flood Risk

Sir James Bevan KCMG, Chief Executive of the Environment Agency, has warned that surface water is the UK’s biggest flood risk and highlighted potentially dire consequences if action is not stepped up to tackle the issue.

Speaking at the October CIWEM Surface Water Management Conference, he described surface water flooding as “a real and growing threat” to life, property, the economy and the country which impacts the whole infrastructure – road, rail, utilities etc – of a town or city.


Sir James outlined a nightmare scenario where London was overwhelmed by intense rain during the summer leading to flash floods, resulting in deaths and the city grinding to a halt.

He reminded people that a smaller version of this happened in 1975 when a localised thunder storm dropped more than three months of rain in three hours. Four of the capital’s main-line railway stations were flooded and closed while much of the underground was brought to a standstill as tunnels were inundated and electrics failed.


He went on to say that the 2007 summer floods were a “wakeup call for us all” – causing 13 deaths, flooding of 44,600 homes and £3 billion in damage.

The event led to the 2008 Pitt Review, which concluded that much of the flooding had arisen not from rivers over-topping but from surface water. The resulting Flood and Water Management Act (2010):

  • provided clarity on the roles and responsibilities of the Environment Agency, local authorities, water and sewerage companies and others who manage flood risks
  • prompted the agency to make many changes, including better information on areas at higher risk from surface water flooding, improved forecasting and a record £2.6 billion investment in flood defence construction projects to better protect 300,000 homes by 2021
  • improved the way the agency works with natural processes – using nature to help manage flood risk and adopting greener approaches to engineering.


However, Sir James warned that future challenges are growing, including:

  • climate change, which will bring more extreme rainfall
  • development and building more houses for an increasing population, all of which have potential to increase the risk of surface water flooding
  • constructing modern infrastructure which does not increase the risk of surface water flooding and is more resilient to it when it happens.


He said the challenges would only be met by “pressing all the buttons that are available to us, and by doing it together” to improve how we manage surface water flood risk both now and in future.

Defra’s Surface Water Management Action Plan published in July 2018, seeks to strengthen the current arrangements by improving collective understanding of the risks and helping those responsible to manage them effectively. It also promotes better partnership working across all the flood risk management authorities, better risk assessments, better data sharing, and better guidance.


Sir James emphasised the need to design resilience into towns and cities, part of which involved Sustainable Drainage Systems.

However designing in resilience was “about a lot more than SUDs” and meant starting “far upstream in the planning process so that new developments are themselves laid out in ways which reduce surface water and other risks.”

He also warned that “the wrong kind of farming in the wrong place can cause significant surface water flooding”.

He also stressed the need for greater public awareness to ensure people at risk were better prepared – whether by putting in property level protection or encouraging their local council to ensure that the risks are mitigated.


External Sources

Water Briefing website: Surface water – Environment Agency chief warns UK’s biggest flood risk is growing