Research and analysis

Wessex water situation: October 2025 summary

Updated 12 November 2025

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

1. Summary

Following the preceding wet September, October was a slightly drier month. An average of 88mm of rain, 88% of the long term average (LTA) fell across Wessex during October. Despite September, this has been the fifth driest 8-month period (March to October) since records began in 1871. During October, most rain fell during the latter half of the month. Soil moisture deficit (SMD) decreased through most of October apart from a brief interlude of rising SMD during the first half of the month. Monthly mean flows recorded across Wessex in October were largely normal or below normal. Daily mean flows in October peaked during the latter half of the month. Most groundwater sites reported notably or exceptionally low levels at the end of October. Overall reservoir levels for Wessex water were approximately 33% capacity at the end of October while for Bristol Water, levels were approximately 34% capacity.

2. Rainfall

An average of 88mm of rain fell across Wessex in October (88% of the LTA). Despite September being wet, this has been the fifth driest 8-month period (March to October) since records began in 1871. Most days in the first half of October were dry excluding between 2 and 3 October when 21mm fell across Wessex. The wettest day of the month was 19 October with an average of 19mm of rain across Wessex (21% of rain during October). In total 75% of the month’s rain fell during the latter half of the month between 18 and 31 October. The highest relative rainfall was recorded in the Lower Hampshire Avon which received 116mm of rain (114% of the LTA). The lowest relative rainfall was recorded in the Brue which received 77mm (84% of the LTA). Overall, rainfall was normal in all hydrological areas of Wessex in October.

Over the past 3 months, all hydrological areas in Wessex have received normal rainfall except for the West Somerset Streams which received below normal rainfall. Over the past 6 months, most areas to the north of Wessex received below normal rainfall while most areas to the west of Wessex received notably low rainfall. Four areas to the south of Wessex have received normal rainfall over the past 6 months. Over the past 12 months, most hydrological areas to the south and west of Wessex received below normal rainfall while most areas to the north of Wessex received notably low rainfall.

3. Soil moisture

SMD in Wessex initially decreased in response to rain on 2 and 3 October. Following this SMD increased slightly until the middle of the month. From the middle of October, SMD decreased for the remainder of the month. Across most hydrological areas in Wessex, SMD was in the range of 41mm to 70mm at the end of October. For all but 3 hydrological areas, SMD was between 6mm and 25mm greater than the LTA.

4. River flows

In October, most flow sites in Wessex recorded either normal or below normal monthly mean flows. The only exceptions were the Dorset Stour at Throop and Wylye at South Newton which recorded notably and exceptionally low monthly mean flows respectively. Daily mean flows for most sites across Wessex peaked during the latter half of October in response to the rain from 19 October.

5. Groundwater levels   

At the end of October, the majority of groundwater sites in Wessex reported either notably or exceptionally low groundwater levels. Chitterne Down (monitoring the Chalk) and Didmarton (monitoring the Inferior Oolite) were the only sites to report below normal groundwater levels at the end of October. Allington (monitoring the Great Oolite) was the only site to report normal groundwater levels. All sites which reported exceptionally low groundwater levels at the end of October were monitoring the Chalk aquifer. For the majority of sites in Wessex including all those monitoring the Chalk, groundwater levels continued to decrease throughout most of October. At faster responding sites such as Didmarton and Over Compton (monitoring the Bridport Sand), groundwater levels rose slightly towards the end of October.

6. Reservoir stocks

Both Wessex Water and Bristol Water reservoir levels slightly decreased during October. The combined levels at the end of the month for Wessex Water were approximately 33% capacity while for Bristol Water, combined levels were approximately 34% capacity. For Wessex Water, this is notably lower than this time last year while for Bristol Water, this is only slightly lower than last year.

Author: Wessex Hydrology, Hydrology.Wessex@environment-agency.gov.uk

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.