Uisce Éireann has issued boil water notices for parts of Waterford and Tipperary due to strike action arising from a dispute between the Unite trade union and a number of local authorities.
Water service workers took part in work stoppages yesterday and today.
Unite is seeking a commitment that water staff transferring from local authorities to Uisce Éireann will retain their public service status.
The utility company said the boil water notices may remain in place for several days and there is potential for disruption to water services in 12 local authorities.
Plants on boil water notices in Waterford and Tipperary are Adamstown, Stradbally, Ballylaneen, Crotty's Lake, Templetney, Glenary and Poulavanogue.
Galtee was added today due to raw water issues as a result of heavy rain.
Other counties which could be impacted by the strike action and potential disruption to supply include Cork city, Cork county, Kerry, Fingal, South Dublin County Council, Dún Laoghaire-Rathdown, Louth, Carlow, Galway city and Wexford.
Tom Cuddy, Head of Operations for Uisce Éireann, said: "There have been a small number of burst and power outages in the last 24 hours and we would again appeal to Unite to ensure essential services are maintained and / or allow access to non-Unite members to access these locations."
