When faced with a flood or flood warning, it is important you have the right information to fully understand the risks, how to mitigate them and what to do in the event of a flood. See below for advice on all aspects of flooding and the risks this carries.

What is a flood?

A flood is described as "where land not normally covered by water becomes covered by water."

What are the different types of flood and what are the risks to my property?

There are a number of causes of flooding. A property can be flooded by:

Surface water flooding in times of heavy rain

In prolonged, exceptionally heavy downpours, which are becoming more frequent, the ground may become saturated and the drains and sewers which carry away surface water may not be able to cope, leading to surface water flooding. Although this is more likely in low-lying areas, and to premises at the foot of slopes, it can happen to many other properties which are not specifically designated as being at risk of flooding on the Environment Agency's flood risk maps
Surface water flooding may be triggered or made worse in urban areas where the ground consists of mostly hard surfaces such as concrete or tarmac so the rainwater flows straight off rather than soaks away into the ground. It is estimated that nearly 4m properties are at risk of surface water flooding in the UK. Surface water flooding can affect one or two individual properties at a time, or may affect many more where this kind of flooding extends throughout the neighbourhood.

Sewer flooding

When sewage escapes from the pipe through a manhole, drain, or by backing up through toilets, baths and sinks this is known as sewer flooding. Sewer flooding can be caused by: a blockage in a sewer pipe; a failure of equipment too much water entering the sewers from storm run-off (from roads and fields) and rivers and watercourses which overflowed; or the sewer being too small to deal with the amount of sewage entering it. The cause of the problem may be some distance away from where the flooding is happening. If the sewage enters a building, it is called 'internal flooding'. If it floods gardens, or surrounding areas such as roads or public spaces, it is called 'external flooding'.

Groundwater flooding

Rising groundwater levels resulting from heavier rainfall and reduced abstractions can present problems. Groundwater flooding generally occurs during long and intense rainfall when infiltration into the ground raises the level of the water table until it exceeds ground levels. It is most common in low-lying areas overlain by porous soils and rocks, or in areas with a naturally high water table.

Irrespective of whether water shows at the surface, rising groundwater levels are posing an increased threat to buildings with basements. Such flooding may occur separately or in conjunction with flooding from other sources such as surface water flooding.

River flooding

River flooding occurs when rivers and streams are unable to carry away floodwaters within their usual drainage channels. Adjacent low-lying properties and land are then liable to be flooded. River flooding can cause widespread and extensive damage because of the sheer volume of water, and may be longer-lasting and more difficult to drain away. Fast-flowing floodwaters can also be a threat to peoples' and animals' safety and can structurally damage buildings. Breaches in reservoirs pose a particular hazard, with the potential to release large quantities of water if the failure is catastrophic.

Coastal flooding

Coastal flooding is caused by high tides coinciding with a low-pressure storm system which raises sea and tidal water levels, overwhelming coastal defences. This may be made worse by gale force winds blowing the raised body of water onto the coast. Coastal flooding may affect not only property on the coast itself but also property in tidal river basins some distance from the coast, due to floodwater being forced up the tidal reaches of rivers and estuaries by raised sea levels and gales. Such flooding may become more frequent in future years due to rising sea levels.

Reservoir or dam failure

The UK has approximately 5,000 reservoirs. Many of these were created by building a dam across a river or stream. Dam failures in the UK are however uncommon. Nevertheless, there are a significant number of "large" raised reservoirs in the UK which may pose a potential risk. It is recognised that whilst the chances of reservoir failure are remote the consequences are potentially catastrophic and could affect areas several kilometres from the dam itself. A flood can happen to any property, from one or more of these causes.

(Flooding definitions with kind permission of the RICS Clear Guide To Flooding)

Flooding is a real risk and should be considered by all homeowners. If you are one of the 5 million people in England and Wales who live or work in a floodplain, your home or business is more likely to be flooded than it is to catch fire. Most people know what to do in the event of a fire but would you and your family know what action to take before a flood and when a flood arrives at your home?

For help with writing a flood plan visit please click here.

Flood Re - the Future of Flood Insurance

In April 2016 a not-for-profit scheme called Flood Re came into effect in the UK. This has been designed to ensure flood insurance remains widely affordable and available.

Hundreds of thousands of people in the UK live at risk of being flooded and had previously lived in fear of both individual property and community blight.

The key aspects of Flood Re are:

  • A cap on flood insurance premiums.
  • Caps are linked to property council tax bands.
  • The Flood Re pool is funded through a new industry-backed levy. All UK household insurers have to contribute to the levy, creating a fund that can be used to pay claims for people in high-risk homes.
  • Flood Re is to be in place until 2039.

The premium cap for the flood component of a policy will result in a typical saving of between 30-40% on overall policy premiums for properties in high flood risk areas.

The Flood Re pool is set at £180 million for the first five years, which equates to around £10.50 for each household in the UK with both buildings and contents policy.

But what will not be included in Flood Re?

Houses built post 2009 are excluded (consistent with the previous agreement known as the Statement of Principles.) We believe it is very important that building in areas of flood risk is not incentivised. It would be foolish to allow properties being built today, in an era of good flood mapping and modelling, to get subsidised flood insurance. If the planning system is right and works properly then there shouldn’t be any homes in this post-2009 category that would need help.

Other exclusions also apply – largely (but not entirely) business premises - for more detail on this, please see: https://www.floodre.co.uk/homeowner/eligibility/

One of the aspects of Flood Re that gets our thumbs up to is that it also includes surface water flooding, which represents the majority of flood insurance claims. Another favourable aspect is that if a policy holder is put into Flood Re and takes moves to protect their home from being flooded and can prove that they have reduced their risk, they can be taken out of Flood Re and pay less for their insurance.

Details of how to protect your home from being flooded can be found in our Homeowners Guide to Flood Resilience download here.

Who can assist during a flood?

The Environment Agency is responsible for building, maintaining and operating flood defences and for issuing flood warnings to the public, other flood responding organisations and the media. The Environment Agency also provides the Floodline 0845 988 1188 service. You can listen to recorded information on flooding for your area or speak to an operator for advice 24 hours a day.

Floodline - sign up to Floodline Warnings Direct.

Floodline is also available in Scotland, coordinated by the Scottish Environment Protection Agency (SEPA).

Natural Resources Wales (English)

Natural Resources Wales (Welsh)