People are being urged to play their part, with a hosepipe ban now in place across the country.
It will remain in force until the end of the month, as supplies remain dangerously low.
With most of the country in the grip of drought and temperatures set to rise over the weekend, Irish Water says it could take months for levels in rivers and lakes to return to normal.
The company’s Kate Gannon explains how the hosepipe ban will be enforced:
