A hosepipe ban is being introduced in the south and southeast of the country this weekend following a sharp increase in demand for water since the start of the summer.
Uisce Éireann said the conservation order will be in place for counties Tipperary, Waterford, Wexford and Cork - excluding Cork city - from Saturday.
It will continue for seven-and-a-half weeks, until Tuesday 16 September.
A similar ban is already in effect for Mullingar in Co Westmeath, Milford in Co Donegal, and the Kells and Oldcastle areas of Co Meath, until Monday 4 August.
Uisce Éireann said the use of a hosepipe for one hour is the equivalent of the daily water usage for an average family.
The ban covers garden hoses and other non-essential uses of water by domestic users as well as commercial premises for non-commercial activities, such as watering a garden attached to a premises.
People in the four impacted counties will be prohibited from using garden hoses for non-essential uses of water such as filling up pools or washing cars or watering their garden.
Uisce Éireann said that a significant number of water supplies around the country are under pressure - with almost 50 in drought status - because of demand.
This has put increased pressure on rivers and other water sources, many of which are at historically low levels following a drier than normal autumn, winter and spring.
The company said that, in recent weeks, it has taken steps to maintain and protect supplies and reduce demand to sustainable levels.
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Uisce Éireann appealed to customers, irrespective of whether their supply is covered by a hosepipe ban, to be mindful of their water use and to report leaks in the system.
Asset Strategy Manager Mairéad Conlon said: "The past 12 months have been drier than normal when compared to the long-term average" and "while recent rainfall has brought some respite, it will take much longer for all our supplies to recover".
"The situation is compounded by recent increased demand in the south of the country which is associated with warm weather and other factors such as tourist activity in some areas".
