Uisce Éireann says a hotline will be available for people to report others who breach a hosepipe ban.
The six-week conservation order comes into effect from Thursday for Dublin, South Tipperary and parts of Kildare, Meath, Wicklow and Wexford. It runs until Wednesday the 26th of August.
The utility is warning the hosepipe ban could be extended to other areas of the country if the hot, dry weather continues.
Treated water supplies have come under pressure as usage has increased significantly as the country enters the second week of heatwave conditions.
Under the water conservation order, households are being asked not to use hosepipe or power washers in their gardens or to wash their car.
Filling paddling pools or 'ornamental' ponds is also not allowed.
Hosepipe. Image: incamerastock/AlamyMargaret Attridge, Head of Water Operations at Uisce Éireann, said people can contact their customer care line on - 1800 278 278 - to report people who break the conservation order.
"We're providing a hotline because we're not asking people to confront people. We don't want to cause any neighborhood disputes here.
"People can contact us and we will follow up with individuals.
"And look, normally, once people understand the ask and the importance of the ask to conserve water for really essential uses, they'll work with us and there's no further action required."