A boil water notice impacting more than 615,000 people has been lifted with immediate effect, Irish Water has said.
The restrictions had been in place for parts of Dublin, Kildare, and Meath for over a week.
The decision comes after the Health Service Executive, the Environmental Protection Agency, Irish Water and Fingal County Council reviewed test results from samples at the Leixlip Water Treatment Plant.
Results from an earlier test carried out last week had returned satisfactory, but the Health Service Executive and EPA requested more tests be conducted.
Irish Water said the current problem at the Co Kildare facility was the result of very heavy rainfall that washed large amounts of organic matter into reservoirs.
This increased the turbidity or cloudiness of the source water at the Leixlip plant.
It had left more than 615,000 people in parts of Dublin, Kildare and Meath under instruction to boil water before use.
It was the second boil water notice issued for water from the plant in recent weeks.