Seven water companies are bringing in water restrictions that will affect 20 million people.
Hosepipes will be banned across the south and east of England from tomorrow.
Thames Water said its hosepipe ban, which will apply to 8.8 million customers, was about prioritising the most important uses of water to prevent tougher restrictions later in the year.
Millions of homeowners have been banned from using hosepipes from today as drought grips parts of the country.
Deep underground, the drying-up boreholes of East Sussex show the extent of the UK's drought problem.
20 million people across the south and east of England will be hit by hosepipe bans that have come into effect since midnight.