Kurow consumers are having to boil their water while the Waitaki District Council investigates whether it has become contaminated.
The ''boil water'' notice was issued on November 23 after a test returned a hit on the presence of E. coli.
Usually, the water source is so good it does not need chlorination, but the presence of E. coli in the system itself has prompted the warning.
Assets group manager Neil Jorgensen said the council was investigating whether the contamination was a sample error, one-off or something in the pipelines.
For example, there could have been some form of blowback from a hose.
If the contamination persisted, the council would have to looks at treatment options.
In the meantime, residents have been told to take precautionary measures when cleaning their teeth, bathing or preparing any food that has to be washed.
