More rain is needed to replenish levels in some aquifers, a water firm has said.
South East Water, which supplies 2.1m customers in Kent, Sussex, Surrey, Hampshire and Berkshire, said the aquifers provided 75% of its supply.
Autumn and winter rainfall was vital if they were to continue recovering from the most recent drought, the firm said.
Although reservoirs are full after a damp summer, some of the deeper aquifers remain very low.
The company said demand for water had dropped by about 5% compared with the same period last year, equating to nearly 30m litres less water being used each day.