Hosepipe bans could be slapped on at least 17 million Britons who would risk £1,000 fines if they were caught flouting the restriction.
Almost a million people across Hampshire and the Isle of Wight who are supplied by Southern Water are subject to the ban, which will come into effect on Friday, after severely below average rainfall over the last eight months in what has so far been one of the driest years on record.
The dry weather is causing other companies such as Thames Water, South East Water and Welsh Water to also consider bans and they are calling on their combined 17.3 million customers to cut back on how much they use.
An Environment Agency spokesman said: “Southern Water’s announcement of a temporary-use ban for its customers in Hampshire and the Isle of Wight is one of many measures they and other water companies should consider to reduce unnecessary use of water and protect customer supplies and the environment.”
Some 935,000 people living in about 500,000 properties will be affected by Southern Water's temporary use ban, which is the first in the region since 2012.
Steve Turner, an expert at the UK Centre for Ecology and Hydrology, said: "There is no suggestion of wetter weather in southern areas of the UK in the near future.
"If that is the case, it is likely that river flows, groundwater levels and reservoir stocks will continue to decline in the south of the country.
"This would increase the short-term pressure on water supply, and prolonged dry conditions would also mean continued impacts on agriculture and freshwater wildlife."
A majority of England, with the exception of the North West, has moved into a state of "prolonged dry weather", which the Environment Agency has labelled "the first stage of a drought".
Hampshire, in particular, has been massively deprived of rainfall this summer. Some parts of the county such as the village of Odiham have not had a drop of rain throughout the whole of July.
