Research and analysis

Groundwater situation: Sussex, 10 April 2026

Updated 10 April 2026

Applies to England

Current situation

A lot of rain fell in January and February 2026. Some locations recorded twice as much rain as the long term average, in both January and February. However, only a small amount of rain was recorded in March 2026, and so far in April 2026.

Between the middle of January and late February 2026, groundwater rose far and fast. With less rain recently, groundwater has been able to slowly fall since the 23 February 2026. In all Sussex groundwater communities groundwater is still higher than average, but now much lower than in winter. Groundwater is now a few metres below the surface, in most communities, and continues to fall.

Residual, minimal, groundwater flood impacts might continue to affect fields, or roads in the Ems and Lavant valleys in West Sussex groundwater communities. Groundwater will intermittently affect the sewage network’s ability to operate in the Lavant valley.

No groundwater flood impacts are expected to be occurring in East Sussex groundwater communities.

Graph showing changes in groundwater levels in Compton Borehole in West Sussex from February 2024 to April 2026. The graph shows that groundwater levels are currently above average for the time of year but currently falling.

Graph showing changes in groundwater levels in Ladies Mile Borehole near Brighton from February 2024 to April 2026. The graph shows that groundwater levels are currently above average for the time of year but currently falling.

Weather forecast

A weak front and showers could bring brief periods of rain to parts of Sussex over the weekend. Rainfall totals are forecast to be small, with less than 5mm of rain expected on each of the next 5 days to Tuesday 14 April 2026.

Longer term weather forecasting is very difficult. Unsettled weather is suggested to continue through April 2026. However, on average, less rain occurs in spring than winter. All forecasts come with uncertainty, and predictions may change over time.

Forecast risk of flooding

Groundwater is expected to continue to slowly fall in boreholes. Minor groundwater flood impacts should ease in West Sussex communities.

In the Ems Valley near Stoughton and Walderton, in Patcham near Brighton, and in Denton near Newhaven, no new groundwater flood impacts are expected.

In the Lavant valley near Chichester, groundwater could continue to affect the ability of the sewage network to operate in East Dean, Charlton, Singleton and West Dean. Potentially through to mid April.

With only small amounts of rain forecast, and less often, it will become harder for groundwater to rise again this spring and summer. Groundwater flood impacts should ease around mid April 2026 in the Lavant Valley, sooner in many other locations.

It is most likely that groundwater will now continue to fall through the rest of spring and summer. However, the exact groundwater response will depend on the amount, intensity and distribution of any rainfall that occurs.

Groundwater will probably next rise again in October 2026. However, it is very difficult to accurately predict the weather weeks or months ahead, and the forecast might change. If exceptional rainfall occurs, there may be periods where groundwater briefly rises sooner. If we experience a prolonged dry period, groundwater may not rise again until later.

Next update

We will update this groundwater situation document by Friday 16 October 2026, or sooner if the risk of flooding significantly increases.

When in force, groundwater flood alerts are updated with information more frequently.

What we are doing

We continue to monitor groundwater levels and their response to rainfall.

Throughout autumn and winter, we will update this groundwater situation and our groundwater briefing notes.

We will issue and update flood alerts when there is risk of flooding affecting property.

We liaise with the local authority and other responding partners to ensure they are aware of the situation.

Our operational staff will remove blockages from main rivers, to ensure they flow freely.

Actions and advice

Think and prepare now for what you’ll do if flooding occurs where you live, don’t 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. Ensure valuables are moved 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
• water situation reports

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

Contacts

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, you can contact the following for additional information:

• 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