Thames water situation: October 2025 summary
Updated 12 November 2025
Applies to England
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This publication is available at https://www.gov.uk/government/publications/water-situation-local-area-reports/thames-water-situation-october-2025-summary
1. Summary
Thames area received 74mm of rainfall in October, which was 92% of the long term average (LTA). Soil moisture deficits (SMD) decreased across Thames area; from 160mm in September to 123mm by the end of October. Monthly mean river flows were normal or below normal for the time of year. Groundwater levels continued to decline at all but 3 of our indicator sites during October. Groundwater levels ranged from exceptionally low at Rockley (Chalk) to notably high at Frith Cottage and the Flashes (Lower Greensand). Farmoor reservoir and the Lower Thames reservoirs remained below the LTA for the time of the year.
2. Rainfall
Thames area received 74mm of rainfall in October, which was 92% of the LTA. All our areal units received normal rainfall for the time of the year. Rainfall in October largely occurred across 4 days, 3 October, and then the in 4 days leading up to Storm Benjamin, the 19, 20 and 22 October.
3. Soil moisture deficit and recharge
SMD decreased across Thames area; from 160mm in September to 123mm by the end of October. This was still far above the LTA of 70mm for the time of year, indicating that soils are considerably drier than expected. As we have entered the winter period, soils must become fully wetted before recharge to groundwater resources can happen.
4. River flows
Monthly mean flows increased at the 9 of the key indicator sites compared to last month, in response to the wetter conditions. Monthly mean river flows at the majority of our key indicators were normal or below normal for the time of year. The River Coln at Bibury was the only indicator site to record exceptionally low flows due to groundwater levels in the Oolites.
5. Groundwater levels
Groundwater levels continued to decline at all but 3 of our indicator sites during October. Levels ranged from exceptionally low at Rockley (Chalk) to notably high at Frith Cottage and the Flashes (Lower Greensand).
Most sites remained within the same banding as the previous month. However, Rockley (Chalk) dropped from below normal to exceptionally low and Stonor Estate (Chalk) dropped from above normal to normal. Ampney Crucis (Great Oolite) improved from notably low to normal.
Overall, groundwater levels in the Oolites are normal to notably low, the Chalk is normal to exceptionally low, whereas levels in the slower-responding Lower Greensand remain notably high for this time of year.
6. Reservoir stocks
Stocks in Farmoor reservoir increased from 87% to 87.1% during October. Reservoir stocks decreased in the Lower Thames reservoirs and ended the month at 61.5% compared to 63.6% at the end of September. Both the Farmoor reservoir and Lower Thames reservoirs remained below the LTA for the time of the year.
7. Environmental impact
At the end of the month, 27 abstraction licences were being constrained in the area to protect water resources and the environment. There was also 1 flood alert issued.
Author: Thames Area Groundwater Resources and Hydrology, enquiriesWT@environment-agency.gov.uk
Contact details: 030708 506 506