Research and analysis

Wessex water situation: June 2025 summary

Updated 15 July 2025

Applies to England

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

1. Summary

June was a fourth consecutive dry month in Wessex. An average of 46mm, 76% of the long term average (LTA) fell across Wessex, largely during the first couple of weeks. When considered alongside the preceding 3 months, this has been the fourth driest 4-month period (March to June) since records began in 1871. Soil moisture deficit (SMD) initially fell in June due to rain between 1 and 14 June. SMD then rose during the drier latter half of the month. Monthly mean flows recorded across Wessex were largely below normal or notably low. The majority of groundwater sites, including most sites monitoring the Chalk aquifer, reported below normal or notably low levels at the end of June. The only exceptions were Didmarton monitoring the inferior Oolite which recorded normal levels and Oakley Industrial Estate monitoring the Chalk which recorded exceptionally low levels. Overall reservoir levels for Wessex Water were approximately 71% capacity at the end of June while for Bristol Water, levels were approximately 66% capacity at the end of the month.

2. Rainfall

An average of 46mm of rain fell across Wessex in June (76% of the LTA). This is the fourth consecutive relatively dry month, resulting in the driest 4 month period (March to June) since 1976 and the fourth driest 4 month period since records began in 1871. For the Little Avon hydrological area in the north of Wessex, this was the driest 4 month period (March to June) on record. Approximately 90% of rain during June fell during the first couple of weeks between 1 and 14 June. The lowest relative rainfall was recorded in the Parrett (62% of the LTA). The highest relative rainfall was recorded in the West Somerset Streams to the north west and Poole Harbour and Purbeck to the south east of Wessex (98% of the LTA). In June, all hydrological areas in Wessex received normal rainfall. No hydrological area in Wessex received above the LTA for rainfall in June.

Over the past 3 months, most hydrological areas have received between notably and exceptionally low rainfall. The exception areas in west Dorset and west Somerset largely received below normal rainfall. The West Somerset Streams was the only hydrological area to receive normal rainfall over the past 3 months. Over the past 6 months, most hydrological areas to the north of Wessex received below normal rainfall while most areas to the south received normal rainfall. Over the past 12 months, most hydrological areas in Wessex received normal rainfall while a few areas to the south and east received above normal rainfall.

3. Soil moisture

SMD in Wessex initially decreased due to rainfall in the first couple of weeks of June. Over the following drier weeks, SMD increased until the end of the month. The rain early in June kept SMD below the historic maximum throughout June. Across most hydrological areas in Wessex, SMD was in the range of 101mm to 130mm at the end of June. There were a couple of exceptions to the north west which recorded SMD between 71mm and 100mm and several exceptions to the south east which recorded SMD between 131mm and 160mm. For most of the north of Wessex, SMD at the end of June was between 26mm to 50mm greater than the LTA. For most areas in the south of Wessex, SMD was between 51mm to 75mm greater than the LTA.

4. River flows

In June, the majority of flow sites in Wessex reported either below normal or notably low monthly mean flows. The exceptions were 3 sites to the south and west of Wessex which reported normal monthly mean flows and the Bristol Frome at Frenchay which reported exceptionally low flows and its lowest June monthly mean flow on record. Most sites monitoring flows on or downstream of the Chalk aquifer recorded below normal monthly mean flows. The exceptions were the Wylye at South Newton and the Dorset Stour at Throop which both recorded notably low monthly mean flows and the Piddle at Baggs Mill which recorded normal flows. Relative flows were slightly higher across most sites in the south of Wessex are they were supported by baseflow from the Chalk aquifer. For most flow sites in Wessex, daily mean flows increased marginally early in the month in response to the rain between 1 and 14 June and then fell for the remaining weeks.

5. Groundwater levels   

Following 4 consecutive dry months, the majority of groundwater sites in Wessex, including most sites monitoring the Chalk aquifer, ended June reporting either below normal or notably low levels. Oakley Industrial Estate (monitoring the Chalk) was the only site to report exceptionally low levels at the end of June. Didmarton (monitoring the inferior Oolite) in the north of Wessex was the only site to report normal levels at the end of the month. For all monitoring sites, groundwater levels decreased throughout most of June.

6. Reservoir stocks

Both Wessex Water and Bristol Water reservoir levels continued to decrease throughout June. The combined levels at the end of June for Wessex Water were approximately 71% capacity while for Bristol Water, combined levels were approximately 66% capacity. For both water companies this is notably lower than reservoir levels recorded this time last year. For Wessex Water, reservoir levels at the end of June are slightly higher than this time of year in 1995 while for Bristol Water, levels are lower than at the end of June 1995.

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.