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Flood risk investigation

Investigations into significant flood events in the borough.

Flooding on Cowley Road

Role as a Lead Local Flood Authority

The council as a Lead Local Flood Authority (LLFA) under the Flood and Water Management Act. The council has the lead on 'local' surface water, groundwater and ordinary watercourses issues. The Environment Agency has the lead on main river flooding and reservoir flooding and a strategic overview. Although the organisations have the lead on these issues, they does not have the responsibility or the ability to solve all flooding issues, the primary responsibility remains with the landowner.

As an LLFA the council also now has the duty to investigate significant flooding events. This tries to identify the organisations involved, and where they are taking action to alleviate flooding. It is dependant on the cooperation of these other organisations. This writing of the investigation does not mean the council is responsible for the flooding or providing solution to all reports contained within it. However it is hoped that by making the process more transparent, these organisations can be more easily held to account for their actions.

Residents reporting flooding

It is key for the council to understand the full extent of the flooding and reporting the issues after the event is critical. Although reports will be collated from various internal departments and external organisations if you can use this form to report an event, this will ensure you provide all the relevant details needed. Photographs with timestamps are particularly useful.

Please note the form is not to be used to request emergency help or action from the various departments within the council.


Reports of flooding to the council are collated and recorded, and significant flooding (where properties or business have been flooded internally) trigger a Section 19 investigation, which will be published.

Any investigation takes time to prepare, but particularly in Hillingdon as often the places affected are so disparate across the borough. Each report is investigated, further information collected, reviewed, and referred to other organisations such as Thames Water where necessary for feedback. Often there are a number of bodies involved in different parts of the drainage system. For example where gullies on the road, which the council are responsible for, drain to a Thames Water Sewer, which in turn flows into a river.

The council understands the concerns of residents who will wish to see action taken quickly, but it is important that the council understand and prioritise resources and funding to those affected most. The council must also ensure that works do not make the situation worse for others.

Flood Investigation Report December 2013 - June 2014 [1Mb]

Flood Investigation report 28th July 2014 [1Mb]

Flood Investigation Report 23 June 2016 [78Mb]


In the long term, reported flooding sites, from the finalised investigation will then be incorporated into an update of the Hillingdon's Surface Water Management Plan as sites where further investigation will be undertaken to seek solutions for.

These will be prioritised in accordance with the consequences of the flood and the numbers affected against those already on the Action Plan and are being taken forward.

Where possible, the most affected sites will be the subject of applications for external funding on behalf of the relevant service area. This will allow the Council to do more detailed studies of the area and assess options for solutions to determine if there is a future scheme to alleviate flooding. This will often need the cooperation of other bodies who may also be responsible for parts of the drainage system.

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Article utilities:  Bookmark and Share Print Print this page Last updated: 30 Jun 2017 at 16:17