CANCER patients attending a day care clinic in Beaumont Hospital have been warned not to consume water at the unit after it was discovered to contain E-coli and coliforms.
The discovery was made at one of the country's biggest hospitals following routine testing of the hospital, including the radiation oncology unit where the contaminants were found.
The hospital has said no patient or staff member has yet suffered ill health because of the contamination.
All affected units have been identified and disabled and the hospital says no other water sources have been contaminated.
A boil water notice is in place and staff at the hospital, as well as patients attending for radiation therapy, have been provided with bottle water.
E-coli, or Escherichia coli, is a baceterium that is commonly found in the lower intestine of organisms, including people.
Most types of the bacetria are harmless but E-coli can result in conditions ranging from mild gastroenteritis to severe diarrhoea and, in some cases, blood poisoning and kidney failure.
Last week the Environmental Protection Agency (EPA) warned of the dangers of E-coli and said that more than one in ten private wells was contaminated with the bacteria in 2012.