Night-time restrictions on water supplies are being introduced for some 10,000 households and a large number of farmers and creameries in north Cork.
Irish Water say they have had to introduce the restrictions because demand on the Newmarket Regional Water Supply is exceeding supply.
The scheme supplies Newmarket, Kanturk, Tullylease, Kilbrin and Boherbue.
The extended dry weather period means the source for the scheme is coming under increasingly pressure.
'Find and fix' leakage crews have also been put into action to identify and fix water leaks in the area.
Irish Water is asking local community to help by fixing any dripping taps or leaking toilets.
Meanwhile, Irish Water say the water supplies for Cork city are at risk of being "severely" depleted in the absence of significant rainfall over the Lee catchment during the autumn months.
The city's water reserves at Inniscarra, Lee Road & Glashaboy are now being brought into use, according to the company.
Irish Water's Neil Smyth says they are appealling to households and businesses in Cork to do "everything they can to conserve water and reduce demand as much as possible at this critical time".
In Co Kerry, water levels have continued to fall.
Water supply schemes under pressure include the Kerry Central Regional Scheme, which supplies 62,000 customers in Killarney, Tralee, Castlemaine and Castleisland.
Most public water supply schemes on the Dingle Peninsula, and the western parts of the Iveragh Peninsula, are also affected.