A 30-bed step-down unit adjacent to Dublin's Beaumont Hospital has been closed temporarily after the legionella bacteria was found in the water supply.
The bacteria causes legionnaires' disease, but the hospital says no patient has contracted the illness.
The affected unit provides step-down beds for older people and was only opened in the summer.
Patients have been moved to St Joseph's Hospital in Raheny to allow remedial works to be carried out.