1,200 customers had been affected by the fault.
A boil water notice in south Offaly has been lifted with immediate effect.
The advisory had been in place for 1,200 customers supplied by the Dunkerrin Public Water Scheme since September 22.
It followed a mechanical failure at the water treatment plant which affected the disinfection process.
However, Irish Water says the supply has now been deemed safe to drink again after an audit by the Environmental Protection Agency.
Laois Gardaí Thanking Public After Finding Missing Woman
Missing Laois Teenager Found Safe And Well
Man In His 90s Dies In Laois Crash
Offaly Prize Bonds Holder Wins €500k
BNM Workshop Reunion Taking Place In Offaly Tomorrow
ICTU Reminds Employees Of The Right To Disconnect
Laois Town To Host Famine Commemoration Event
Plans For Billion Euro Data Centre In Westmeath Face New Appeal
Westmeath Councillor Advocates For More Remote Working Hubs
Midlands Homelessness On The Rise
Hundreds Without Power In Westmeath
Westmeath Domestic Abuse Support Service Reports Rise In Cases
Laois TD Highlights GP Gap
Call Made For 'Cost Of Disability Payment' in Budget 2027
Offaly Coffee Shop Listed Among Top 100 In Europe
Man To Stand Trial Over Midlands Tasering Accusation
Another Report Underlines Midlands House Price Inflation
Midlands Braced For Severe Thunderstorms
Sustainable Livestock Village Programme Launched For Tullamore Show
Offaly Woman Named National Carer Of The Year