During heavy rain in London in July and early August, the Met Office recorded over a month's worth of rainfall in a few hours in certain areas. The intensity and duration of the rainfall overwhelmed the drainage infrastructure, causing surface water flooding to parts of London.
Under section 19 of the Flood and Water Management Act 2010, a lead local flood authority (unitary authorities and county councils) is required to investigate, to the extent that it considers it necessary or appropriate, flooding incidents, including whether flood risk management authorities have exercised their functions. Once completed the report must be published and the relevant risk management authorities notified.
Following the summer surface water flooding in London, Thames Water has also commissioned an independent review into the performance of its network, including its Maida Vale and Counter's Creek flood defence schemes. The Government expects all relevant risk management authorities, especially lead local flood authorities and water companies, to consider and act upon the outcomes and lessons learnt.
Surface water flooding is a local flood risk; managing this risk alongside flooding from groundwater and ordinary watercourses is the responsibility of lead local flood authorities. This includes ensuring the risk of flooding is identified and managed, as part of a local flood risk management strategy, ensuring contingency arrangements and support for local communities are in place. In managing these local risks, the lead local flood authority will work with other risk management authorities. This includes the local highways authorities, who are responsible for highway and gully maintenance, and the water and sewerage companies who operate and maintain the public sewer network.
Water and sewerage companies are regulated by Ofwat, the independent economic regulator for water. Ofwat will hold the companies to account for the delivery of affordable, secure and resilient water services, and will take enforcement action where necessary e.g. where a water company has breached a duty.