Boiled Water Notice issued by Irish Water.
Cryptosporidium is a parasite which can sometimes cause disease.
Sligo News File.
Public Water supplies to homes in the South and West of Sligo are under investigation for the presence of cryptosporidium.
The parasite is found in the intestinal tract of humans and animals, where it sometimes causes disease.
More than 13,000 people are affected after the Lough Talt Regional Water Supply Scheme was found to be the source of the contamination.
Irish Water have issued a boiled water notice which the utility says will remain in place for at least two weeks.
The notice advises that water be boiled for drinking, food preparation, brushing of teeth and use in ice.
A spokesman for the company this evening attributed the pollution to recent heavy rainfall and run-off into the regional supply.