The Selwyn District Council in Canterbury is advising residents in the Dalethorpe area to begin boiling their water.
The council's water quality monitoring programme has found that due to recent high flows in the Hawkins River, there are unacceptable levels of E.Coli in the water supply.
The council will continue to monitor the intake of water from the river into its reticulation system and will be chlorinating it until further notice.
The council says the Dalethorpe supply does not include Glentunnel, Whitecliff and Coalgate.
