A hosepipe ban has been introduced in Kent and Sussex.
South East Water said it was bringing in the ban amid shortages in those regions.
Schools have been forced to close during the warm weather and bottled water stations have been set up as the utility firm said demand for drinking water has reached “record levels”.
South East Water said the temporary hosepipe restrictions will come into force from 26 June and means customers cannot water their gardens, wash cars, boats or patios and are banned from filling paddling or swimming pools.
The company’s chief executive David Hinton said: “This situation has developed much more rapidly than last year. Understandably, we’ve seen customer demand increase in line with the hotter weather, however this has impacted our ability to keep all customers in supply at all times.
“Despite asking for customers help to use water for essential uses only, regrettably we’ve now been left with no choice but to introduce this temporary use ban restriction to protect customers supplies across Kent and Sussex.
“The long-term forecast for the rest of the summer is for a dry period with little rainfall, although temperatures may reduce slightly.
“Restricting the use of hosepipes and sprinklers to make sure we have enough water for our customers’ essential use, will ensure we can serve our vulnerable customers and to protect the local environment.”