It comes after a week of hot temperatures across the United Kingdom, with the record for the hottest day of the year being set on four consecutive days.
Boil only what you need - people often overfill the kettle when they make a cuppa, think about it next time you make one just for yourself, and make your mantra: "boil only what you need".
A spokesperson said it expected the vast majority of the public will be "law-abiding" and will adhere to the hosepipe ban.
The firm has enacted its contingency plans and increased water production capacity in order to meet the anticipated spike in water use as the warm weather continues.
Fill a bucket with water and grab your sponge, rather than using a pressure washer.
The company did not offer further detail on plans to enforce the ban.
People are not allowed to use a hosepipe to water their garden, wash their vehicle or private boat, or to fill or maintain a swimming or paddling pool, pond or fountain.More news: Mbappé youngest player to score brace in World Cup game since Pele
The ban in the Greater Dublin Area includes Kildare and will run until the end of July. If you are caught doing so, you will be fined €125.
Picture: Getty Why does the hosepipe ban exist?
However, a spokesman said there are no drought restrictions as the company is now supplying an extra 87 million litres of water a day across the region compared with a week ago.
Low water levels in Wayoh Reservoir.
Similar drought orders have been introduced in Northern Ireland and in British water utilities and operate by mobilizing public support for responsible behavior. However, saying that, if any business can conserve water then please do so, every drop counts!
Turning the taps off when you clean your teeth, and reducing your shower-time to the recommended four minutes will also help. "Once you go over that volume then you risk water quality and we can't put out water that's not treated to compliance standards".
Irish Water says that "the primary objective of these orders is to mobilise maximum public support and engagement on minimizing water use during the crisis".