The issue has been caused by the extreme weather over the past few days and the subsequent thaw which has put extreme pressure on the complex underground system of 9,000 miles of pipes which takes drinking water from treatment works into homes.
Thames Water advised its 15 million customers to only use water where essential.
"When water freezes within a pipe it expands, putting more pressure on the pipes and joints, often causing pipes to split or joints to pull apart, and then when it thaws the water will start to leak out".
A lorry arrived in Rotherfield and South East Water workers unloaded huge supplies of bottled water for distribution among residents.
People are urged to have short showers rather than baths, not to leave taps running and to only use dishwashers and washing machines if they're full.
The companies are attempting to fix problems for vulnerable customers first and are providing bottled water where necesarry.
The "Beast From The East" brought snow misery to thousands in the last week, but temperatures are set to reach double figures in the south.
"This will make a real difference", the statement by Thames Water, South East Water, Southern Water and Affinity Water said.
South East Water had asked homeowners, business owners and members of the public to keep an eye out for leaks after 130 million litres of extra water was pumped out across the network on Saturday.
A spokeswoman said they were doing "all we can to get as many customers back on supply as soon as possible" and apologised "sincerely to those without water or with low pressure".