Southern Water has applied for an extension to its drought permit on the Bewl Water reservoir.
Bewl Water was only 37% full at the beginning of 2006
The company is being allowed to refill the depleted reservoir, which supplies customers in Kent and Sussex, with water from the River Medway.
The Environment Agency's drought permit runs until the end of March, but Southern Water has asked for it to continue until the end of April.
Bewl Water should be at 90% capacity but it is only just over half full.
Southern Water's Meyrick Gough said: "If we continue pumping into Bewl until the end of April, it will make a real difference to the reservoir level.
"It is essential we get as much water into Bewl ready for the summer because many water resources across the region, particularly those underground, are at their lowest level ever following back-to-back dry winters."
Southern Water said above average rainfall and higher river flows during February had helped the situation a little.
The original drought permit application was scrutinised over wildlife fears and, according to the Campaign to Protect Rural England, a lack of strategy.