Repair works will leave some homes and businesses in north Dublin without water later today.
Maintenance crews will begin work on the local water main from 11am to 4pm and disruptions are expected.
The main areas affected are Boroimhe and Ridgewood.
"It wouldn't be recommended to drink water from the attic tank, because there's no way of knowing what has been stored there, but it's certainly fine for washing," said Joe Mahon, senior executive engineer with Fingal County Council.
"For preparing food, just before it would be consumed directly, we would recommend that people would boil water from that source but we would certainly envisage that most properties would have 24-hour storage in the attic, and that would certainly be more than enough for the duration of the works today."