"Our four above-ground reservoirs are all well above average for the time of year, as are the underground sources that supply 70 per cent of our water supply and which at the start of the summer were severely depleted," said water quality and strategy manager Meyrick Gough.
"The weather over the past 12 months has been very unpredictable, making life difficult for everyone. This time last year we were feeling the effects of two very dry winters and reservoir and aquifer levels were worryingly low.
"Now we’re in the opposite position and thoughts of a drought and hosepipe ban are very far away. Instead we have some customers experiencing very difficult conditions as a result of the amount of rainfall we have received."
Autumn and winter were important for water companies as this was when reservoirs and underground sources refilled in time for the peak demand seasons of spring and summer, he said.
The Environment Agency said many key groundwater sites in the south east were at "notably high levels or higher" for the time of year, with two aquifers in Sussex reaching record levels in December.
Meyrick added: "We’ve had two dry winters followed by the wettest summer on record – and now we’re experiencing one of the wettest winters. From a water resources point of view we are now in a very strong position ahead of the spring and summer."
Southern Water is currently updating its 25-year plan for securing water supplies in the south east and is including plans to make the water supply for customers more resilient to changing weather patterns in the future.
The Water Resources Management Plan is updated every five years and will be published for public consultation between May and July this year. Visit www.swhaveyoursay.co.uk