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Know your Flood Risk

“Across Wales over 245,000 properties are at risk of flooding from rivers, the sea and surface water with almost 400 properties also at risk from coastal erosion. As the climate changes we can expect those risks to increase, with more frequent and severe floods, rising sea levels and faster rates of erosion of the coast”.

This means that approximately 1 in 8 properties in the whole of Wales are at risk of flooding. Within Rhondda Cynon Taf this figure is reduced to approximately 1 in 5 properties at risk of flooding.

Understanding your flood risk can help you be better prepared and more aware of the threat of flooding in your area.   

The types of flooding and who to contact are shown below.

Main river flooding occurs when river and larger streams cannot contain the flow of water, resulting in overtopping and/or breaching of flood defence structure. Contact Natural Resources Wales in this case.
Flooding from ordinary watercourses involves ditches, drains, culverts and smaller streams that aren’t recognised as main rivers. Flooding can occur when flows in a watercourse exceed capacity and result in overtopping and/or beaching flood defences. Flooding can also be caused by debris build up causing blockages to infrastructure. Contact the Council in this case.
Flooding from surface water or ‘pluvial flooding’ is caused by flash floods which exceeds the capacity of the ground and local drainage networks to absorb it. This can lead to water flowing across the ground and ponding in low-lying areas. Contact the Council in this case.
Flooding from groundwater occurs when water rises from underground, and the soil becomes saturated. This tends to occur after prolonged periods of rainfall. Contact the Council in this case.
Sewer flooding occurs when the capacity of a sewer system is exceeded or failure of a sewer due to a collapse or debris build up in the network. Water and sewerage companies are responsible for this.
Flooding from reservoirs occurs when above ground water storage fails and spills onto the surrounding area. Contact the Reservoir owner.
Flooding from Roads occurs when the volume of rainwater does not drain away through existing drainage systems. Contact the South Wales Trunk Road Agency for flooding from motorways and major trunk roads. Contact the Council as the Highway Authority for flooding from other roads.

Check your flood risk

There are a range of tools available to find out your flood risk. Some of these are freely available online, whereas other more comprehensive assessments will charge.

These tools and services will allow you to understand the potential risk of your property, and a detailed independent flood risk assessment will outline what measures would be suitable for your property. For more information of how to protect your property visit here.

Check your flood risk
Tool / ServiceDescription

Natural Resources Wales


Flood Risk Assessment Wales (FRAW) map


Check your flood risk by postcode service

The free online FRAW map shows your risk of flooding from rivers, the sea, surface water and ordinary watercourses and reservoirs.


The map also provides additional information about your area, such as the location of flood defences, the areas benefitting from flood defences and the areas covered by NRW for free flood warnings and alerts.


View your flood risk on a map here.


You can also check your flood risk by postcode here.


Natural Resources Wales


5-day flood risk forecast for Wales

A 5-day flood risk outlook for Wales is available on NRW’s webpage here. This service is freely available and may indicate if there is an immediate flood risk to your area.


You can also call Floodline 0345 988 1188 – 24 hour service.


Commercial Desktop Flood Search

These are produced by private companies who have access to more detailed flood risk information. They will include the data from free online flood maps but supplement this with information on historical flooding; groundwater flood susceptibility; the position of local watercourses and reservoirs; the local topography and improved information on the local flood defences.


When selecting a search, check that it is provided by a company with good pedigree in environmental data and adequate professional indemnity (PI) cover.

Independent Flood Risk Assessment

It is possible to commission an expert to do a full flood risk survey, including a site inspection. It is advised that you ensure you get an assessment from a chartered surveyor. You can find more information on this through the Royal Institute of Chartered Surveyors (RICS).

Further information on the different types of flood risk (high/medium/low) and understanding your flood risk results from the Flood Risk Assessment Wales map and the Check your flood risk by postcode service can be found on NRW’s website.