Here's a guide to some of the terms we've used.
Airbricks – a specialist replacement brick that replaces the original. This automatically shuts the vents when water enters so to preventing water coming through the holes. Once water subsides the air vents open again.
Airbrick covers - a plastic cover that clips to frames fitted around airbricks on exterior walls, preventing water entry.
Drainage pipe valves - these are one-way valves on drainage pipes to decrease the risk of sewage backing up into a building.
Fluvial (river) flooding - flooding resulting from water levels exceeding the bank level of a river. Flooding from rivers that have been designated as ‘Main River’ is managed by the Environment Agency.
Flooding - floods are normally caused by heavy rainfall over a short period of time or extensive rainfall over a prolonged period. However, human activities such as changes in land use or building in floodplains can also lead to flooding or make it worse. Simply put, a flood is too much water in a place where we humans would rather it wasn’t. The most commonly known source of flooding is river flooding, where a river overtops its banks, but there are other types of flooding that are less obvious but are increasingly affecting us – surface water and groundwater flooding. It’s these sources of flooding that Chesham is most at risk from.
Flood barriers - flood boards, made of plastic or metal, can be installed across a doorway or window before a flood arrives. The boards usually slide into a frame that has been pre-attached to the door or window frame to provide a watertight seal.
Groundwater flooding - flooding from groundwater can happen when the level of water within the rock or soil that makes up the land surface (known as the water table) rises. The level of the water table changes with the seasons due to variations in long term rainfall and water abstraction. When the water table rises and reaches ground level, water starts to emerge on the surface and flooding can happen.
Local flooding – this can be caused by intense rainfall before it enters a watercourse or sewer (surface water flooding), water flowing over the land because of high groundwater levels, the capacity of the sewer network being exceeded and ‘out of bank flow’ from small watercourses (those not designated as ‘Main River’, which come under the responsibility of the Environment Agency).
Sandbags - these are available from builders merchants as well as online sources. Bin bags filled with soil are an alternative option. These can be used to create a dam in front of doorways and can also be put in a toilet bowl to prevent toilets from overflowing. They must be thrown away after flooding because they may be contaminated.
Surface water flooding – is caused by rainwater (including snow and other precipitation) which is on the surface of the ground (whether or not it is moving), and has not entered a watercourse, drainage system or public sewer.
Waterproof bags - these can be large enough to cover furniture.