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Groundwater Flood Risk


Understanding Groundwater Flood Risk

We’ve compiled guidance, useful Data, Downloads and Videos. We also organise Continuous Professional Development training events.

What is Groundwater?

Groundwater is any water found beneath the surface that fills pores or cracks in the underlying soil and rocks. It contributes 30 per cent of public supply water in England. In volume terms, this is over six thousand million litres per day enough to fill 2500 Olympic-sized swimming pools every day, or run a dishwasher 400 million times*

Groundwater levels are higher in winter and reach a peak in the spring. During periods of prolonged high rainfall, the level of groundwater rises to the surface, beyond its normal range, which causes flooding.

*BGS data 2019

What is Groundwater flooding?

Groundwater flooding can be highly disruptive, lasting several months, and can cause more extensive longer term damage to property. This can include:

  • New springs developing and sudden water movement
  • Basement flooding
  • Overloaded sewers
  • Economic disruption and cost up to 30 days after surface flooding
  • Agricultural losses

Find out more about how GeoSmart can assist in relation to Groundwater at your Site here.

How does Groundwater impact on Development Sites?

You may have purchased a site with a view to develop it, or you are an architect with a client who needs to appraise the site for master planning submission or to meet conditions.

In both instances, you need to know the drainage characteristics and whether groundwater could have an impact on the surface water flood management and sustainable drainage approach, as determined by the Local Planning Authority. If the site has an industrial past, there may be contaminants in the soil which could be spread by groundwater.

Our contaminated land assessments, Flood Risk Assessment Reports and Drainage Reports will guide you to make the right decision s to meet planning requirements.

How do I know I am at risk?

Groundwater is most commonly found in low-lying areas underlain by aquifers, such as Chalk or sandstone, or localised sands or river gravels in valley bottoms.

It is especially common in southern and eastern England, as well as parts of the Cotswolds, East Yorkshire and Eastern Pennines.

Alerts are now in place for residents who sign up to text alerts with the Environment Agency in affected areas.

GeoSmart provides the Flood Forecasting Centre with alerts on the future risk of groundwater flooding

Groundwater Flood Forecasting

What is at risk from groundwater flooding?

The two infographics below clearly demonstrate the number of properties and critical infrastructure that are at risk from groundwater flooding.

How does groundwater cause sewer flooding?

Groundwater can have a significant impact on critical wastewater networks. High levels of groundwater can access the sewer network through cracks in pipes or access chambers. This can mix to affect the local water table and be a significant risk to communities and businesses.

GeoSmart works with a numbers of water companies to provide alerts to them so they can manage their assets to protect communities.

Groundwater Sewer Infiltration Flood Forecasting




Here is a video by Wessex Water on how groundwater can impact sewer systems

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We also run a regular series of webinars and can provide in-house seminars to ensure your team is up to speed on the latest requirements and support their CPD needs.