A 100-day drought is affecting the Thames Water region, with the Environment Agency declaring the dry spell on July 29.
Water resources in London and the Thames Valley remain under pressure.
Rainfall across the region totalled only 34 per cent of the amount recorded between 1 March and 30 September 2024, according to figures covering the equivalent 2026 period.
Julie Morton, Thames Water’s head of water resources, described the prolonged dry conditions and five heatwaves as having placed considerable pressure on regional water supplies.
The company said recent rainfall had provided some relief, but a drought built up over several months would require time to reverse.
Saturated ground conditions are slowing the recovery process.
A relatively dry forecast is expected for the first half of November, making sustained autumn and winter rainfall necessary to restore water reserves before spring and summer.
Thames Water has thanked customers for continuing to conserve water while its teams work to protect supplies and the environment.
As of 3 November, Farmoor Reservoir was holding 76 per cent of its capacity, while aggregate reservoir storage in London stood at 56 per cent.
The utility has maintained a high rate of leakage repairs, resolving more than 1,000 leaks every week.
That represents approximately 20 per cent more repairs than normal levels.
A Temporary Use Ban remains in force for every Thames Water customer.