Research and analysis

Kent and South London water situation: April 2025 summary

Updated 14 May 2025

Applies to England

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

1. Summary

The whole of the Kent and South London (KSL) area received 51% of the long term average (LTA) rainfall during April. Rainfall received was below normal across most catchments. Soil moisture deficits (SMDs) increased in all catchments. Across the whole KSL area, on average, effective rainfall received this month was at 10% of the LTA. Monthly mean flows (MMFs) ranged from normal to below normal in April in KSL. Four out of the 11 key flow sites saw below normal MMFs and 3 saw notably low MMFs. Groundwater levels in the Chalk are normal for this time of year at the end of April. Groundwater levels at the Lower Greensand aquifer at Riverhead decreased but continues to register above normal levels. Levels at the end of the month at the 5 water company reservoirs in the area ranged from below normal to notably high.

2. Rainfall

The whole of the KSL area received 51% of the LTA rainfall during April. Rainfall received was below normal across most catchments. Two catchments received normal rainfall. The percentage of LTA rainfall received ranged from 36% in the Upper Mole in the West to 69% in the Northwest Grain area in the North. In the previous 3 months, spanning from February to April, notably low rainfall was recorded in most catchments with below normal recorded in 3 catchments in the south and one exceptionally low in the East. In the previous 6 months, from November to April, rainfall was normal across catchments in the south and below normal in catchments in the North. In the last 12 months, rainfall ranged from above normal to notably low in KSL area. Above normal rainfall was recorded in the Medway catchment in the centre, whilst normal and below normal were recorded in the remaining area. The highest daily rainfall total of 20.8mm for April was recorded at Brede PS TBR in the Eastern Rother catchment on 22 April. The next highest daily rainfall totals were on 14, 15, 23 and 13 March and ranged from 4.2mm to 18.3mm. Eight days with less than 0.3mm of rainfall was recorded this month.

3. Soil moisture deficit and recharge

At the end of March, Soil moisture deficits ranged from 26 to 34mm in most catchments. At the end of April soil moisture deficits increased ranging from 41 to 130mm. In March, all catchments registered slightly higher SMDs than long-term average. SMDs increased in all catchments due to the lack of effective rainfall in April. Across the whole area, on average, effective rainfall received this month was at 10% of the LTA. In April, the difference from LTA increased in all catchments.

4. River flows

MMFs ranged from normal to notably low in March in KSL. River Wandle at Connolly’s Mill in the northwest, River Darent at Hawley, River Eden and Vexour/Penshurst and River Dour at Crabble Mill in the east saw normal flows. River Dour at Crabble Mill recorded the highest MMF percentage LTA of 106% for the month of April. Four out of the 11 key flow sites saw below normal MMFs. The River Medway at Teston, the River Rother at Udiam, East Stour at South Willesborough and River Stour at Horton saw below normal flows. Three out of the 11 key flow sites saw notably low MMFs. The River Mole at Dorking, the River Ravensbourne at Catford and River Teise at Stonebridge saw notably low flows. River Ravensbourne at Catford and the river Mole at Dorking recorded the lowest percentage LTA of 39%. The fall in MMFs is consistent with the effective rainfall of 10% of the LTA and the SMDs registered by the end of April.

5. Groundwater levels       

At the end of April, groundwater levels in the Chalk were normal for this time of year. Groundwater levels at the Lower Greensand aquifer at Riverhead have continued to decrease but remain above normal. Groundwater levels in the Chalk are continuing to fall since the end of last month or are now starting to decrease in all key monitoring points. The fall in groundwater levels is consistent with the effective rainfall of 10% of the LTA and the SMDs registered by the end of April.

6. Reservoir stocks

Throughout April, water levels in all the water company reservoirs declined somewhat marginally.

At the end of April, reservoir levels were:

• below normal at Darwell at 92% full

• normal at Bewl with 94% full and Weir Wood with 100% full

• above normal at Powdermill at 100% full

• notably high at Bough Beech at 100% full. Weir Wood reservoir remained offline during April

7. Environmental impact

On 3 April, widespread constraints were applied to abstractors in the Medway catchment, with licences linked to Teston gauging station, and these persisted throughout the month. Similarly, on 28 April, constraints were imposed on abstractors in the Stour catchment, with licences linked to Wye gauging station, and these remained in effect for the rest of the month.

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

Contact Details: 03708 506 507

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.