The notice has been in place since earlier this week.
The boil water notice has been lifted for customers of the Leixlip Water Treatment Plant.
Irish Water confirmed the lift today, stating on Twitter that the notice had been removed with immediate effect.
The affected areas were parts of Dublin, Meath, and Kildare. Approximately 600,000 people were affected by the notice.
"Boil Water Notice for customers supplied by the Leixlip Water Treatment Plant has been lifted with immediate effect," said Irish Water.
"We are grateful to our partners in @Fingalcoco who worked with us to provide all necessary detail to the HSE & EPA to facilitate the lifting of this notice."
https://twitter.com/IrishWater/status/1187755914578812930?s=20
The areas affected by this week's boil water notice were as follows:
Artane, Ashtown, Balbriggan, Baldoyle, Ballyboghill, Celbridge, Clonee, Clonsilla, Coolock, Coolquoy, Corduff, Darndale, Donabate, Dunboyne, Finglas, Garristown, Glasnevin, Howth, Kilbarrack, Kilclone, Killester, Kinsaley, Leixlip, Lusk, Malahide, Maynooth, Naul, Palmerstown, Poppintree, Ronanstown, Rush, Skerries, St Margaret's, Straffan, Sutton and Swords.
The notice was issued for homes and businesses in the vicinity of the Leixlip Water Treatment Plant earlier this week.
The entire water supply had been affected.
Irish Water's statement is as follows:
"Following consultation with the HSE, Irish Water and Fingal County Council can confirm that the Boil Water Notice for customers supplied by Leixlip Water Treatment Plant has just been lifted with immediate effect.
"The EPA conducted an audit of the Leixlip Water Treatment Plant on Thursday. Irish Water and Fingal County Council were on site to support the audit. The HSE were also present. The test results of a water sample that was taken earlier in the week was found to be satisfactory and this result formed part of the audit process.
"This lunchtime, Irish water received the results for two more water samples taken later in the week. Both samples were satisfactory."
