Factsheet: Groundwater flooding
What is groundwater flooding?
Groundwater flooding is caused by unusually high groundwater levels. It occurs as excess water emerges at the ground surface or within underground structures such as basements. Groundwater flooding tends to be more persistent than surface water flooding, in some cases lasting for weeks or months, and it can result in significant damage to property.
The risk of damage caused by groundwater flooding can be considered less if the property does not have a basement. However, it can not be discarded completely as it could still negatively impact the property.
It is important to note that groundwater is often excluded from the flood element of house insurance, and we recommend reviewing any policies you may have.
What is the data based on?
Groundwater flood data is provided by Ambiental Risk Analytics. The Groundwater flood risk of the report is a result of a combination of the local geology and topography features present for which groundwater flooding could potentially occur.
This data is based on a 5m Digital Terrain Model (DTM) and 1 in 100 year return period.
Further guidance on groundwater flooding is available from the Environment Agency.
What should a purchaser do next (residential)?
We would recommend the following next steps are considered:- If the house has a basement or other section below ground, investigate whether tanking/lining is possible. This is a process where basement areas are sealed with a watertight material to prevent groundwater seeping in;
- Look at the search result in the context of its locality. Discuss with the seller (and potentially their neighbours) to see if groundwater flooding is common there and what measures are in place to combat it;
- Consider conducting a visual check at the property looking for water staining, damp patches or mould growth. Be aware of any damp smells. It is also worth checking the survey to see if any of these things have been reported;
- Make enquiries of the seller (e.g. in the TA6) and other nearby residents on any flooding that may have occurred;
- Sign up to the Environment Agency's Flood Warnings and Alerts https://www.gov.uk/sign-up-for-flood-warnings;
- Investigate the various forms of flood resistance and resilience measures that will help protect your property in the event of a flood;
- Create a flood plan https://check-for-flooding.service.gov.uk/plan-ahead-for-flooding.