Tunisia has extended its quota system for tap water along with a ban on using it for agriculture until further notice, the Agriculture Ministry said on Saturday.
In March, the North African country began cutting off water at night and banned its use for agriculture, in response to a drought that has lasted five years.
Authorities said at the time the measures would remain in place until September 30.
The use of tap water to wash cars, water green areas and clean streets and public places has also been banned.
Anyone who breaks the rules faces a fine and imprisonment for up to six months.
In recent years, Tunisia has experienced longer summers and periods of drought, placing additional pressure on already depleted groundwater sources.
Tunisian dams recorded a fall in capacity of about one billion cubic metres, due to low rainfall from September last year to mid-March this year.
Sidi Salem Dam, in the north-west of the country, is the main source of drinking water for several regions. The level there has dropped to 16 per cent of its 580 million-cubic-metre capacity.
The impact of climate change has been blamed for prolonged droughts across parts of the world.
