Research and analysis

Groundwater situation: Hampshire 14 March 2025

Updated 14 March 2025

Current situation

Groundwater levels across Hampshire are high for the time of year. At most rain gauges in Hampshire, February 2025 was wetter than normal, with between 45 and 100mm of rain recorded across the county.

This is between 60 and 170% of the long-term average expected for this month.

The beginning of March has been very dry with all rain gauges recording between 0 and 4mm of rainfall.

Groundwater levels have been rising during March in response to very heavy rainfall recorded at the end of February.

However, in most communities, the levels have now stabilised and are beginning to slowly fall.

Groundwater flooding impacts are ongoing in several susceptible communities. Impacts include:

• winterbourne streams flowing
• flooding to land, roads and cellars
• the inundation of sewerage systems and septic tanks

Graph showing changes in groundwater levels in Clanville Gate Borehole in North Hampshire from January 2023 to March 2025. The graph shows groundwater levels rising steadily from the beginning to October 2024 until now. Groundwater levels are very high for this time of year but have just stabilised and started slowly falling.

Graph showing changes in groundwater levels in Hursley Borehole in central Hampshire from January 2023 to March 2025. The graph shows an incline in groundwater level from the beginning of October 2024 until early March 2025. Since then, groundwater levels have been relatively stable.

Graph showing changes in groundwater levels in Whitedale Farm Borehole in East Hampshire from January 2023 to March 2025. The graph shows a steady incline in groundwater level from the beginning of October 2024 until now. Groundwater levels are average for this time of year and have just stabilised and started to slowly fall.

Weather forecast

Over the next 5 days, only small amounts of rain are forecast to affect Hampshire. It is possible that more unsettled conditions could return towards the end of next week.

Groundwater levels in Hampshire are expected to continue slowly falling over the course of the next week.

Long range forecasting is difficult. Through the end of March, changeable weather patterns are most likely.

This means periods of unsettled, wet and windy weather interspersed with some drier and brighter spells.

Into early April, there may be a transition to more-frequent drier and settled spells.

Forecast risk of flooding

In most years, groundwater levels typically reach a peak in March or early April and then start to fall as winter rain eases, temperatures rise, and plants start to grow and take up water.

With groundwater levels, currently peaking and beginning to fall, we would expect that groundwater levels in Hampshire will generally continue to fall slowly and ongoing flooding impacts will decrease as we move into spring.

However, groundwater levels remain very sensitive to heavy rainfall. If heavy or persistent rain does affect Hampshire during late-March or early April, groundwater levels may begin to rise once more, and flood risk could increase.

The additional communities most at risk of groundwater flooding impacts in the coming weeks are the villages close to Winchester, Kings Somborne and Little Somborne, and Hambledon.

Next update

We will update this groundwater situation document by Friday 11 April 2025. When in force, groundwater flood alerts are updated with information more frequently.

What the Environment Agency are doing

We will:

• continue to monitor groundwater levels and their response to rainfall 
• update this groundwater situation document and our groundwater briefing notes throughout autumn and winter
• issue and update flood alerts when there is risk of flooding affecting property
• liaise with the local authority and other responding partners to make sure they are aware of the situation
• remove blockages from main rivers, to make sure they flow freely

Actions and advice

Think and prepare now for what you will do if flooding occurs where you live, do not wait until flooding happens. 

Call Floodline on 0345 988 118 or visit check for flooding to find out if you can register to receive free flood alerts for flooding from groundwater. 

Look for data in your area: 

• groundwater data  
• river, sea, groundwater and rainfall levels  

There is practical advice on what to do before, during and after groundwater flooding, and further guidance about groundwater flooding, how it might affect you and what to do. 

Prepare a personal flood plan or community flood plan to help you and your community decide what practical actions to take before and during a flood, which will help reduce the damage flooding could cause. 

Check pumps and any other flood protection equipment you have. Move valuables from basements and other low parts of properties. 

Where safe to do so, communities may wish to check and ensure there are no blockages in local watercourses and ditches.

Further information

You can view: 

• daily groundwater levels compared to average and maximum, with indicative impact thresholds  
• sub daily groundwater levels on Gaugemap 
• the latest flood alert information 
• groundwater situation information for North Hampshire (Alton, Basingstoke, Crondall, Farringdon, Sherborne St John) 
• water situation reports  

More detailed groundwater briefing notes are emailed as part of the flood alert service. See contacts section to register your email address.

Contact

For more information on the flood alert service and to find out what messages you are registered to receive, call Floodline on 0345 988 118. 

Alternatively, for more information, you can contact: 

• Environment Agency Customers and Engagement: ssdenquiries@environment-agency.gov.uk 
• Environment Agency Incident Reporting Hotline: 0800 807060 
• Environment Agency National Customer Contact Centre: 03708 506 506