Selwyn District Council has advised residents who are on the Rolleston Water Supply including the IZONE Business Park to immediately begin boiling water.
Test results revealed today that E. coli levels were above recommended levels in the Council's deep bores.
E.coli is an organism which can cause health issues. People are advised to visit their doctors if they are showing any symptoms of sickness, including vomiting and diarrhoea.
The affected well which showed a higher than recommended E. coli count has been switched off from the main Rolleston water supply to prevent further contamination and the Council has begun chlorinating the water supply.
Any updates will be posted online at www.selwyn.govt.nz.