A hosepipe ban is to come into force across the country from Tuesday June 9th until Tuesday July 21st.
Irish Water says this is after May was the driest month here since 1850.
The utility says a National Water Conservation Order was issued as increased domestic and commercial demand is expected.
It prohibits the use of garden hoses and other non-essential uses of water.
Niall Gleeson, managing director of Irish Water, told Newstalk Breakfast the recent good weather has caused the move.
"I think we all know that the spring we've had is one of the direst springs on record around the country.
"And that weather looks like it's going to continue.
"And that has put a lot of our water sources in drought: we've 27 sites in drought at moment, another 50 are in near-drought - and the longer range forecast from Met Éireann don't show this changing.
"Because of that dry period we need a considerable amount of rainfall in order for those sources to recover".
He explained: "Because people are working from home and have been confined to their homes, we've seen a 20% increase in domestic use across the country.
"This use actually peaks during the warm weather we've had recently".
During the June bank holiday, the warm weather saw an equivalent daily increase of water usage for an additional 200,000 people being used in the Dublin area.
Irish Water said this increase in demand was replicated across the country, but this demand dropped again when the weather turned cooler.
Mr Gleeson said: "That shows that people are using water for what we would say are non-essential activities - filling pools or washing cars or using power hoses or watering their garden with the hose.
"So it's that excess water we're trying to capture".
Met Éireann data shows that temperatures were above average in nearly all areas last month, and rainfall totals in every county were below average for the season.
The greater Dublin area, Westmeath, Sligo and Tipperary saw their driest spring on record.
Irish Water’s data shows dramatic spikes of water usage on very sunny days.
The prohibited uses are use of water drawn through a hosepipe or similar apparatus for:
- watering a garden
- cleaning a private motor-vehicle using a domestic hosepipe
- cleaning a private leisure boat
- filling or maintaining a domestic swimming or paddling pool (except when using hand held containers filled directly from a tap)
- filling or maintaining a domestic pond (excluding fish ponds)
- filling or maintaining an ornamental fountain (with the exception of such use for commercial purposes)
- filling or replenishing an artificial pond, lake or similar application
People who break the conservation ban could face a fine of €125.