The Republic of Ireland's water supplier is introducing a country wide six-week hosepipe ban but NI Water says it has no plans to make the same move.
Uisce Éireann's (formerly Irish Water) Water Conservation Order (WCO) begins just after midnight on Friday and will be in place until Wednesday 26 August.
It said a high demand for water and prolonged periods of low rainfall levels were behind the decision.
NI Water said it was not considering a hosepipe ban.
Earlier in July heatwave conditions were met in Northern Ireland for the second time during the summer when temperatures climbed above 25C for three days in a row.
A heat warning was also issued in the Republic of Ireland due to high temperatures.
Nationwide hosepipe ban
Last week, Uisce Éireann's WCO was introduced for the greater Dublin area and parts of Wexford, Wicklow, Meath, Kildare and south Tipperary but will now apply across the country.
The water supplier said a WCO is only introduced if "absolutely necessary" and encourages people to only use water for essential purposes.
"Conserving and reducing water consumption in these circumstances is critical to ensure continuity of supply," said Uisce Éireann.
The WCO prohibits the use of a hosepipe for watering a garden, cleaning a car or boat, or filling a paddling pool, pond or fountain.
Meanwhile NI Water said while it was not considering a hosepipe ban it encouraged everyone to "keep up their water-saving efforts as demand remains much higher than normal during the warm weather".
A spokesperson said it continues to monitor reservoir levels, which remain at a "reasonable position for this time of year".
NI Water's head of water, Paul Bryce said: "While we are not currently considering a hosepipe ban, we cannot take our water supply for granted.
"We would encourage everyone to continue taking simple steps to reduce water use while the warm weather continues.
"Every drop counts. By continuing to use water wisely, customers can help reduce pressure on the network and help ensure water continues to be available for everyone who needs it."
The company also reminded the public to stay safe around reservoirs during the warm weather as they can be extremely cold, deep and dangerous.