Irish Water says people in the Cashelard area of south Donegal now have safe drinking water.
It follows the removal of the area’s water supply from the Environmental Protection Agency’s remedial action list.
There had been inadequate treatment on the area’s scheme to prevent the formation of so-called THMs.
Some studies have suggested a link between long-exposure to THMs and cancer.
Upgrade works have now removed the risk from THMs on the Cashelard scheme, ensuring people on that supply now having a safe, secure and reliable water supply
There are currently five other supplies in County Donegal on the EPA’s Remedial Action List; they are Creeslough, Glenties-Ardara, Greencastle, Letterkenny and Milford-Letterkenny.
Dr Pat O Sullivan, Irish Water Regional Compliance Lead, says the latest development is good news after several years for people in Cashelard.