Much of England and Wales could face water shortages next year, the Environment Agency has warned.
Six water companies have initiated drought management plans
An exceptionally dry summer and autumn has put water supplies under intense pressure, with much winter rainfall needed despite the recent wet spell.
From January to October this year, the rainfall in England and Wales was the lowest it had been for the same period since 1959.
That led to reduced river flows and a big drop in reservoir water levels.
The Environment Agency says that unless rainfall is 20% higher than average this winter there could be water shortages and drought next year.
The South East has been the worst affected, despite the current wet weather, but even in Scotland there has been concern about next year's water supplies after an unusually dry autumn.
The five driest places in England and Wales between August and October were all in southern England, with Brize Norton in Oxfordshire heading the list. It had 27% of its long-term average rainfall.
One river in Sussex, the Eastern Rother, is running at only 8% of its long-term average, but the Dorset Stour, the Yscir in South Wales and the Soar in the Midlands have all had record low flows.
The agency says the refilling of groundwater (subterranean) supplies across the south is likely to be "uncharacteristically late and poor" in many places.
Groundwater levels in the chalk which underlies much of the region are especially low, with parts of the South Downs now close to the lowest levels on record.
There is also concern over surface water supplies in reservoirs, which are lowest across southern England from east to west, and also in the north-west.
The problem is usually a combination of too little rain, too much falling too fast to do any good, and soil which is unable to absorb the downpours.
Six water companies have already initiated drought management plans to ensure
supplies to customers remain unaffected, and the Environment Agency is urging everyone to conserve water.
It is calculated that if all the adults in England and Wales turned the tap off while cleaning their teeth, it would save 180 million litres of water a day.
Aileen Kiermond from the Environment Agency said: "We've had a fantastic dry spell and that sort of dry spell usually doesn't call for any special action even though we've had a beautiful summer.
"[But if the dry spell continues] through the autumn and winter, we need to secure water supplies so that we can hold off the need for any sort of restrictions as long as possible."