A boil water notice has been issued for around 500 people in Co Limerick.
Irish Water made the decision following a consultation with the HSE and the city and county council. Customers served by the Fedamore public supply are affected by the notice.
The utility said the notice has been put in place following an increase in turbidity - or cloudiness - at the underground borehole source which supplies the area.
They added that this has led to a risk of the treatment process being compromised.
Irish Water said drinking water compliance and operational experts are working with colleagues in Limerick City and County Council to resolve the issue as soon as possible.
"We acknowledge the impact and inconvenience caused by the imposition of a Boil Water Notice to homes and businesses," said Ian O'Mahony, Irish Water's Operations Lead for Limerick.
" We wish to thank the community for their patience and cooperation while we work to resolve this issue.
"Our priority is the provision of safe, clean drinking water and safeguarding that water supply for the future is a vital focus.""
The notice will remain in place until further notice.