A boil water notice has been re-issued for 500 people in Co Limerick.
The warning in place for the Fedamore Public Supply had been lifted late last week.
However, Irish Water has again said due to an increase in cloudiness the treatment process has been compromised.
All customers in the area are advised to boil their supply before use, until further notice.
Ian O'Mahony, Irish Water's Operations Lead for Limerick, said the company acknowledge the impact and inconvenience caused by the imposition of a Boil Water Notice to homes and businesses.
Irish Water also said it is contacting registered vulnerable customers who are affected by this Boil Water Notice to advise them.