A six-week hosepipe ban for six areas around the country has come into effect, while Met Éireann has issued a new Status Yellow heat warning.
The water conservation order is for Dublin, south Tipperary, parts of Kildare, Meath, Wexford and Wicklow, and it will remain in place until 26 August.
Uisce Éireann has urged people to reduce their non-essential water use to protect supplies for homes, hospitals, vulnerable customers and essential services.
Under the order, activities such as watering gardens with a hose, washing vehicles and filling paddling pools are banned in order to conserve water.
Uisce Éireann said the ban could end earlier if conditions improve, or be extended if necessary depending on weather conditions.
It also said further bans are being actively considered for other areas of the country.
Night-time restrictions are also in place on 39 water supplies.
These mainly affect parts of Donegal, Cavan, Longford, Meath, Galway, Laois, Tipperary, Limerick, Kerry, Cork, Waterford, Kilkenny and Wexford.
Uisce Éireann said the recent warm weather has led to a significant increase in water use across the affected areas.
Meanwhile, Met Éireann have issued another Status Yellow high temperature warning, which will come into effect at 12pm tomorrow. This warning is for Carlow, Kilkenny, Laois, Offaly, Wexford, Cork, Limerick, Tipperary and Waterford.
It will come to an end at 8pm tomorrow.
Most of the country remains under an existing Status Yellow high temperature warning, which will come to an end tomorrow morning.
This warning is for Carlow, Kildare, Kilkenny, Laois, Longford, Offaly, Westmeath, Cavan, Donegal, Munster and Connacht.
Met Éireann warns of water safety issues due to increased use of lakes, beaches and waterways; uncomfortable sleeping conditions; heat stress; forest fires; and drought conditions.
Coillte, the semi-state forestry company, said there is a high risk of forest fires. Retailers are being asked to suspend the sale of disposable barbecues for the present time.
Next week, the Cabinet will discuss proposals for an outright ban on disposable barbecues across Ireland’s national parks.
Heads of bill are being drafted by Minister of State for Nature, Heritage and Biodiversity Christopher O’Sullivan.