Research and analysis

Groundwater situation: Sussex, 13 March 2026

Updated 13 March 2026

Applies to England

1. Current situation

2026 has been very wet. In January and February all our rain gauges recorded more rain than average. Some locations recorded twice as much rain as the long term average, in both January and February. Only a small amount of rain has been recorded in March 2026, so far.

Groundwater was at an average level at the start of January. Between the middle of January 2026 and the middle of February 2026, groundwater rose far and fast. Another significant rainfall event on 18 February 2026 caused groundwater to rise again. Groundwater remains higher than average. In all Sussex groundwater communities groundwater is high and close to the surface. However, with less rain at the end of February, and at the start of March, groundwater has been able to slowly fall since the 23 February 2026.

Groundwater flood impacts are expected to be occurring in West Sussex groundwater communities. Water will be flowing in fields, along roads, and in a small number of basements in the Ems Valley, and Lavant Valley. In addition, in the Lavant Valley, water is affecting the sewage network’s ability to operate.

Groundwater flood impacts are not expected to be occurring in East Sussex.

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

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

2. Weather forecast

Only small amounts of rain are forecast over the weekend, and into next week. Less than 5mm of rain on each of the next 5 days to Tuesday 17 March 2026.

Longer term weather forecasting is very difficult. High pressure is thought to bring settled weather to the south east of England for the rest of March and into April 2026. Although there is a suggestion that a brief period of unsettled weather may cause rain to return during the last week of March. All forecasts come with uncertainty, and predictions may change over time.

3. Forecast risk of flooding

Groundwater is expected to continue to slowly fall in boreholes.

However, minor groundwater flood impacts are likely to continue in West Sussex communities until April 2026.

In the Ems Valley near Stoughton and Walderton, springs will appear, water will be in fields, flowing down roads (including along Stoughton main road, the road from East Marden, between Cooks Lane and Barley Mow in Walderton, and the B2146 near Woodlands Lane), water will affect a small number of cellars in Stoughton and Walderton.

In the Lavant valley near Chichester, springs will appear, water will be in fields, water will flow down roads near East Dean, groundwater will appear in a small number of basements, and groundwater will affect the ability of the sewage network to operate in East Dean, Charlton, Singleton and West Dean.

In Patcham and Denton near Newhaven, no groundwater flood impacts are expected.

With only small amounts of rain forecast, and less often, it will become harder for groundwater to rise again this spring. Groundwater flood impacts will remain minor, and should ease by April 2026, sooner in some locations.

However, the exact groundwater response will depend on the amount, intensity and distribution of any rainfall that occurs.

It is very difficult to accurately predict the weather weeks or months ahead, and the forecast might change.

If there is an exceptional rainfall event in the next few weeks, flood impacts could increase a little, or continue for longer.

4. Next update

We will update this groundwater situation document by Friday 27 March 2026, or sooner if the risk of flooding significantly increases.

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

5. 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.

6. 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.

7. 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.

8. 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