Flooding happens from a variety of sources, often in combination.
Flood risk takes into account the harm that a flood actually causes. It is a combination of the chance of an event happening and the impact if it were to occur.
Local flood risk
Groundwater (saturated conditions reaching the ground surface) occurs when rainfall makes the groundwater table rise above its normal level. This type of flooding can last for weeks or months and is most likely to occur in areas above an aquifer.
Other sources of flood risk
These sources of flooding are managed by other organisations, known as risk management authorities, who are better equipped to respond to these types of flooding than the Council. To find out more on how they do this, see our other flood authorities page.
Burst water mains can cause localised disruption to transport links and damage to buildings, particularly properties with a basement. This type of flooding is not related to rainfall.
Sewer flooding occurs when sewers are overwhelmed by heavy rainfall or when pipes become blocked In urban areas, surface water flooding and sewer flooding often combine, polluting floodwater.
Reservoir flooding occurs after the failure of the reservoir’s walls or earth embankments. This may be caused by erosion due to seepage, overtopping of the dam or by accidental damage to the structure. Reservoir failure is extremely rare in the UK.