Thames water situation: August 2026 summary
Updated 14 September 2026
Applies to England
© Crown copyright 2026
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This publication is available at https://www.gov.uk/government/publications/water-situation-local-area-reports/thames-water-situation-august-2026-summary
1. Summary
Despite some rainfall at the end of the month, August was another drier than average month. Thames area received 28mm of rainfall, equivalent to 45% of the long term average (LTA). Thames area remained in drought status, having entered drought in July. Soil moisture deficits (SMDs) were still much higher than expected for the time of year. Monthly mean river flows decreased at all river indicator sites across Thames area. Groundwater levels continued their seasonal decline and ranged from exceptionally low to notably high across Thames area at the end of August.
2. Rainfall
Thames area received a total of 28mm of rainfall in August, 45% of the LTA for the month. The start of the month was drier, less than 1 mm of rain had fallen by 17 August. More than three-quarters of the month’s rainfall fell in the last week of August, with 26 and 29 August accounting for half of the month’s rainfall, totalling 14mm. Two hydrological areas, the Lower Wey and the Cut, received exceptionally low rainfall, equivalent to about a quarter of their LTAs, with totals of 16mm and 15mm respectively. The Thame, Loddon, North Downs Hampshire and Wey Greensand hydrological areas received notably low, while the remaining areas received below normal rainfall compared to their LTAs. Thames area remained in drought status, having entered drought in July.
3. Soil moisture deficit and recharge
SMDs continued to increase across the hydrological areas, with Thames area reaching almost twice its end of August LTA. SMDs in both the Cotswolds East and Cotswolds West areas were approximately double their respective LTA. Effective rainfall was negligible during the month, even in areas that would typically receive some at this time of year.
4. River flows
Monthly mean river flows continued to decrease at all indicator sites across Thames area. Two thirds (10 of 15) of our indicator sites were classified as notably low or exceptionally low for the time of year. Exceptionally low flows were recorded at: the River Thame at Wheatley, the River Coln at Bibury, the River Kennet at Calcot, and at three sites on the River Thames; Kingston, Kingston (naturalised), and Windsor. The monthly mean flow of the River Thames at Kingston was 20% of the LTA. The remaining 5 sites were classified as normal for the time of year. The West Berkshire Groundwater Scheme was switched on towards the end of the month in order to supplement the flows in the River Thames and to bolster the water available for abstraction in the Lower Thames during the drought.
5. Groundwater levels
Groundwater levels continued their seasonal decline at all indicator sites in August. At the end of the month, 5 of our 11 indicator sites remained normal for the time of year. Groundwater levels in the chalk and Lower Greensand aquifers continued to be relatively resilient through the drought, resulting from storage of the above average winter rainfall. The lower storage oolite aquifers are showing less resilience. The only change from July was at Jackaments Bottom, in the Inferior Oolite, which declined from notably low to exceptionally low for the time of year. Levels at Rockley (Berkshire Downs Chalk) remained below normal. Ampney Crucis (Great Oolite) and Model Farm (Upper Greensand) also remained below normal. The Flashes (Lower Greensand) continued to have higher levels than typical for the time of year, with notably high levels.
6. Reservoir stocks
Farmoor Reservoir’s storage decreased to 75.6% at the end of the month, down from 91.8% at the end of July, and was below the LTA for the time of year. Storage in the Lower Thames Reservoirs also decreased, ending the month at 59.4%, down from 72.4% at the end of July, and was also below the LTA.
7. Environmental impact
At the end of August, 41 abstraction licences were having their flows constrained to protect the environment.
Author: Thames Area Groundwater Resources and Hydrology, enquiriesWT@environment-agency.gov.uk
Contact Details: 030708 506 506
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 herein.