Map disclaimer

This map is for indicative purposes only. It provides a general overview of flood risk and should not be used to assess flood risk for individual properties. While every effort has been made to ensure data accuracy, the council assumes no liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system.

All intellectual property rights in the data and information contained in the map are owned by the council or licensed from 3rd party providers. For 3rd party data, please contact the relevant organisations directly.

Government data used by the council can be obtained from the Environment Agency Customer and Engagement team for Hertfordshire and North London: HNLenquiries@environment-agency.gov.uk.

This map should not replace a site-specific flood risk assessment, which is required for planning applications.

Rivers

This map shows the location of rivers within the borough of Hillingdon. Sources include:

• main river: Information is obtained from the Environment Agency.
• ordinary watercourses and other ditches: Identified through variety methods, some unverified.

These rivers may be above or below ground, and there may also be further rivers not identified on this map.

Please note: That if your deeds show you own up to the top of a river bank you may be responsible for maintaining that river. For further information, see guidance provided by Land Registry.

This map should not be used for site specific flood risk assessments or development proposals to determine the exact line and width or top of bank of any river. Rivers move and evolve over time and a site specific assessment should always be undertaken. However, for insurance purposes it can give an approximate distance to the nearest watercourse.

Thames Water outfalls    

These are shown as green triangles. This map provides an indication of Thames Water outfalls. This data has been obtained from Thames Water Utilities Ltd and is edited to show outfalls from the Thames Water surface water drainage network into rivers.

Flood risk from rivers

This map provides an indication of flood risk from rivers.

The Functional Floodplain (Flood Zone 3B)

This zone is shaded light green. Flood zone 3b is defined by the Planning Practice Guidance. The zone comprises land where water has to flow or be stored in times of flood. This is identified by the council in their Strategic Flood Risk Assessment.

No development other than 'water compatible' or 'essential infrastructure' is appropriate in this zone.

Flood Zone 3A and 2

• Flood Zone 1 is shown as clear and is all land outside Zones 2 and 3
• Flood Zone 2 is shaded hatched dark blue
• Flood Zone 3a is hatched light blue

The council uses the Government information shown on the 'long term flood risk assessment for locations in England' for modelled flood extents. You can view Flood Zones 3 and 2 on the Government website.

Surface water flood risk areas

This area is shaded purple. This map provides an indication of areas at risk of surface water flooding. The council uses the Government information shown on the 'long term flood risk assessment for locations in England' for modelled flood extents. You can view this on the Government website.  There are no amendments that the council have made to this mapping.

Critical drainage areas

This area is shown hatched dark purple. This map provides an indication of critical drainage areas. Critical drainage areas may be within Flood Zone 1 (little or no risk) but which has critical drainage problems. They include the catchment area that contributes to the critical drainage problems as well as the area which has the drainage problems. The council has identified these through the surface water management plan.

Licence to use

You may

• view this map
• download a map
• print screen pages
• You may use this map for personal use only
• You must (where you do any of the above)
  • acknowledge the council (and that of any identified contributors) as the authors of the maps contents
  • ensure that you do not use the maps contents in a way that suggests any official status or that we endorse you or your use of the information
  • ensure that you do not mislead others or misrepresent the information or its source .
• Unless you own or control the relevant rights in the material, you must not
  • republish material from this website (including republication on another website)
  • sell, rent or sub-license material from our website
  • show any material from our website in public
  • exploit material from our website for a commercial purpose
  • redistribute material from our website.

Flood and water information map

Use the map to understand general flood risks in your area.

Access the flood and water risk map

Please note: 

• The map is for general guidance only and not suitable for assessing flood risk for individual properties.
• Data sources include the Environment Agency, Thames Water, and the council's own assessments.
• Users must not rely on this map for planning applications or legal decisions.
• Intellectual property rights apply; usage is limited to personal, non-commercial purposes.