Almost half of the population of Co Longford is subject to a boil water notice which was issued on Thursday.
It comes after the cryptosporidium barrier at a treatment plant was compromised following a deterioration in the raw water quality of the lake source, Irish Water said.
Following consultation with the HSE, Irish Water and Longford County Council decided to issue a boil water notice for the area supplied by the Longford Central Public Water Supply to protect public health.
The population impacted by this notice is approximately 17,500 people. The areas affected include all customers in Longford Town, Newtown Forbes, Balinalee, part of Edgeworthstown, part of Drumlish, part of Killashee and surrounding areas.
Experts from Irish Water and Longford County Council are assessing the situation with a view to having the notice lifted as quickly as possible. In the meantime, all customers of this supply are advised to boil water before use until further notice.
John Gavin, asset operations lead, Irish Water, has acknowledged the impact this notice will have on the community and apologised for the inconvenience to customers.
“We are working closely with Longford County Council to restore drinking water quality for all impacted customers. We will monitor the supply over the coming week and will seek to lift the notice in consultation with the HSE as quickly as it is safe to do so. Works are underway at the Lough Forbes plant to increase its capacity, provide increased resilience, and safeguard the supply for the future.”
Vulnerable customers who have concerns can contact the Irish Water customer care team on 1800 278 278.
Updates will be available on the Irish Water Supply Updates section on water.ie including a map of the affected area, on Twitter @IWCare and via their customer care helpline, open 24/7 on 1800 278 278.