The next parts of the South East to be hit by hosepipe bans are likely to be along the Sussex coast, according to Southern Water.
The North Sussex ban currently in force affects 100,000 homes
Warnings came after water use soared by 20% across Surrey and Sussex during the weekend heatwave. North Sussex is currently covered by a hosepipe ban.
Operations manager John Crook said the situation was being monitored closely.
He said increased use was "taking more water from stocks than we have got left and are trying to preserve."
Mr Crook said there was "a strong chance" of more hosepipe bans if hot weather continued and demand for water increased.
"If I was a betting man, I would probably say it is quite likely in parts of the Sussex coast area," he said.
"Obviously, if we can cut down on what we all do in terms of garden water, and try not to waste water, we might be able to put that off."
He said water use restrictions were being brought in so that current stock would last through the dry summer and into the winter.
Southern Water provides water supply and wastewater treatment services across Kent, East and West Sussex, Hampshire and the Isle of Wight.