Irish Water will be taking water samples all over this weekend to test water quality in parts of Dublin, Kildare and Meath.
The boil water notice for more than 600,000 people in these counties will stay in place until Tuesday.
The samples will be brought to its labs to be analysed, after an EPA audit of the Leixlip Water Treatment plant found three samples taken during the week were satisfactory.
Head of Customer Operations at Irish Water, Yvonne Harris says they need to take further samples.
"The Leixlip site is operating and producing clean water," said Ms Harris.
"However, in conjunction with the agencies it was agreed that a number of samples need to be taken over the weekend to ensure that the treated water is reaching all of our customers in the greater Dublin area."
