Research and analysis

Kent and South London water situation: October 2025 summary

Updated 12 November 2025

Applies to England

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

1. Summary

During October, the Kent and South London and East Sussex (KSLES) area received 123% of the long-term average (LTA) rainfall for the time of year, based on a whole-area average. Rainfall received across individual catchments ranged from normal to above normal, all catchments received LTA rainfall above 100%. Soil moisture deficits (SMDs) in all catchments but one decreased during the month of October. SMDs decreased across most catchments, though they remained 4.5% above the LTA overall. Effective rainfall was just 41% of the LTA, with SMDs ranging from 23 to 171mm by month-end. River flows were mostly normal, except for below normal monthly mean flows (MMFs) at Ravensbourne. Daily mean flows (DMFs) varied, with groundwater-fed sites showing steadier flows and clay catchments showing flashier responses. Groundwater levels in the Chalk aquifer showed variation across the area, with Chipstead recording notably low levels and Little Bucket falling to below normal. In contrast, Riddles Lane levels rose to above normal. In the Greensand aquifer, Riverhead also remained at an above normal level. Reservoir stocks showed mixed trends: Bewl, Bough Beech, and Powdermill declined early in the month, while Darwell and Weir Wood levels rose.

2. Rainfall

During October, the KSLES area received 123% of the LTA rainfall for the time of year, based on a whole-area average. Rainfall received across individual catchments ranged from normal to above normal. The percentage of LTA rainfall received ranged from 109% in the Thanet Chalk catchment to 137% in the North Kent Chalk catchment. The highest daily rainfall total of 46.4mm was observed on the 22 day of the month at Brede rain gauge in the Eastern Rother catchment.

Rainfall was particularly notable and widespread across the patch on 3 occasions; the third day, the nineteenth to the twenty second and the last day of the month. The first wet spell was a result of the first storm of the 2025 to 2026 season, Storm Amy. The remaining events were attributed to South Easterly heavy showers and unsettled conditions.

October featured three dry days across the KSLES area, defined as a day with 0.2 mm or less of recorded rainfall. This occurred on 7, 17 and 18 October. This was caused by high pressure system that brought settled conditions and persistent cloud in the middle of the month between storm Amy and the rainfall event on the 22 of the month.

3. Soil moisture deficit and recharge

SMDs in all catchments but one decreased during the month of October. At the end of October, SMDs throughout the KSLES area were, on average, 4.5% higher than the LTA for this time of year. Most catchments exhibited a notable decrease in SMDs in October with many in the south of the patch having the lowest soil moisture deficits since March. This change has been influenced by the increased effective rainfall received across the area during October, which amounted to just 41% of the LTA. At the end of October, SMDs ranged from 23 to 171mm, whereas at the end of September, these ranged from 114 to 208mm.

4. River flows

MMFs at key indicator sites for October were predominantly normal across the area. Below normal MMFs were recorded at the Ravensbourne at Catford in the northwest.

DMFs continued to show considerable variability across most sites, reflecting the distribution of rainfall and effective rainfall throughout the month. Flow peaks were less pronounced – but still evident – at sites supported by groundwater base flow, such as the Dour at Crabble Mill. In contrast, flashy sites influenced by clay-rich catchments, including the Ravensbourne at Catford and the Mole at Dorking, exhibited more marked fluctuations in DMFs in response to heavy rainfall received in October.

5. Groundwater levels   

Groundwater levels in the Chalk across the KSLES area showed variation (still falling and starting to rise) at the end of October. At Chipstead, in the western part of the patch, levels fell steadily from late September and were notably low by month-end. Little Bucket also saw a decline, recording below normal levels. In contrast, Sweeps Lane, Fleete Reservoir, and Wolverton all registered normal levels, with Fleete Reservoir and Wolverton showing a slight rise while remaining within the normal range. Riddles Lane experienced an increase in October and reached above normal levels. In the Greensand aquifer, groundwater levels at Riverhead rose slightly and remained above normal. The variation in groundwater levels is likely due to the higher effective rainfall received this month, combined with elevated SMDs. In areas like Chipstead, much of the rainfall has been absorbed by the dry soil, limiting recharge to the aquifer.

6. Reservoir stocks

Of the five water company reservoirs in KSLES, Bewl, Bough Beech and Powdermill experienced steady declines in water levels in the first half of October that then stabilised in the second half of the month. Levels at Darwell reservoir and Weir Wood reservoir saw a more notable rise in levels, primarily during the last half of the month.

By the end of October, the reservoirs held by the following live storage capacities and LTA class: 

•           Darwell – 47% normal

•           Bewl – 42% below normal

•           Bough Beech – 43% notably low

•           Powdermill – 45% below normal

•           Weir Wood – 99% above normal

7. Environmental impact 

All hands-off flow restrictions were lifted in October, except for a small number of abstractors in the Stour catchment which remained subject to constraints. A limited number of hands-off groundwater level constraints introduced in September continued to apply throughout the month.

Only 3 fluvial flood alerts were issued during October.

Author: Groundwater and Hydrology Team, ksl.gwh@environment-agency.gov.uk

Contact Details: 03708506506

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.