Residents in the Navan area are being advised to boil water before use after it was discovered the town's supply was contaminated with traces of the E.coli bacteria.
Meath County Council is awaiting the results of tests that will determine which strain of e-coli is involved. Most strains of e-coli are harmless when ingested but E.coli O157:H7 can cause severe illness in humans.
The council has said that all water should be boiled for a minimum of ten minutes before before drinking, preparing food, washing or brushing of teeth.
The contamination affects Navan town and outlying areas including Kilberry, Donaghpatrick, Oristown, Gibbstown, Brownstown, Kentstown, Johnstown Village, Walterstown, Lismullen, Balreask, Philpotstown, Gainstown, Tullaghanstown, Bohermeen, Dunderry, Robinstown and Bective.
The source of the contamination, which was discovered during routine testing, has not yet been identified. The council has stated that the instructions to boil water should be adhered to until further notice.