Types of Flooding

In the UK currently, about 1 in 6 homes is at risk of flooding. This could be from a range of sources, and even if a property has never flooded in the past, this does not mean that it is not at risk. In addition to this, in order for a property to flood, it does not need to be located near a river or the sea, or even in low-lying areas. Flooding affects properties all over the UK and in very different ways, with climate change altering weather patterns for the future, it is expected that more areas of the UK could become at risk of flooding. It is essential that you as a homeowner or business owner understand the main types of flooding and what you can do to reduce the damage caused by flooding.

The UK is affected by five main types of flooding UK. These are:

To find out how you can check to see if you are at risk of flooding, please click here. This will provide flood maps for all areas of the UK which highlight a range of flooding types.

You can also find out more about the measures you can put in place on your home or business in the “How to protect your property” section of our site.


River Flooding

River flooding, or fluvial flooding, is a very common type of flooding in the UK. This is where a river’s flow will exceed the bank sides and cause damage or obstruction to a nearby area. Homes and businesses located near streams and rivers should always check their flood risk, to see if they should be worried about river flooding.

River flooding is often fast flowing due to currents from the river itself, if you are walking or driving near a flooded river be very careful and never drive or walk through flowing floodwater. Obstacles may also be carried by river currents, which can even include cars. Just 30cm of fast flowing floodwater can move a car.

Flooded fields by the River Avon in Bath
IMGP1346 – Flooded fields by the River Avon in Bath


Coastal Flooding

Coastal flooding is a type of flooding that affects communities situated close to the sea. With high tides, stormy weather, and climate change all contributing to an increased risk of coastal flooding, this is a major hazard for many areas of the UK. Seawater over topping coastal defences can cause significant damage and disruption to communities, often requiring retreat further inland. With the added problem of salt in the seawater damaging buildings, coastal flooding is a serious issue and should be addressed with appropriate flood protection.

Porthcawl - Sunrise @ High Tide by Gareth Thompson
Porthcawl – Sunrise @ High Tide by Gareth Thompson


Surface Water Flooding

Surface water (also known as pluvial) flooding can affect people all around the country. Even if you are not situated near to a rive or the sea, you may still be at risk of this type of flooding. Surface water flooding occurs after periods of heavy rainfall where excess water cannot drain away. This may be due to a range of reasons including blocked drains or even rainwater running off roads. This water will then collect in an area it cannot drain away from and can cause serious damage. Surface water flood maps are currently available in the UK, but as areas change and develop, this may change where water could collect. Just because your home or business has not flooded before, does not mean that it may not flood in the future.

Carlisle floods 2015 by John Campbell
Carlisle floods 2015 by John Campbell


Groundwater flooding

Groundwater flooding can affect homes and businesses in the UK although this is not the most common type of flooding. For groundwater flooding to occur, the water table in an area must rise as a result of increased rain. When this water table rises up through a slope, there may be a point at which the water table is above the ground level. If this happens, the water will flow over the surface as it cannot seep into the ground – this is groundwater flooding. Unlike other types of flooding, groundwater flooding may require you to consider measures to protect your home that will prevent water from rising up from below your building – such as a floor membrane.

A simple diagram to demonstrate how this type of flooding occurs is available from Southern Water.


Reservoir flooding

Reservoir flooding is extremely rare in the UK due to very strict regulations and mandatory assessments. However, it is still essential to be aware of your risk of reservoir flooding. Reservoir flooding will cause very fast flowing water to flow down the natural water path in large quantities. Get to high ground as quickly as possible.

Reservoir maps are now available for England and Wales, click here for more details. Full details for reservoir owners and operator requirements is available here.

Llyn Clywedog Dam and Reservoir by Freddie Phillips



IMGP1346 by Matt Buck | CC BY-SA 2.0
Porthcawl – Sunrise @ High Tide by Gareth Thompson | CC BY 2.0
Carlisle Floods 2015 by John Campbell | CC0 1.0