Rangitikei District Council staff are confident Marton's water will be running clear in time for anniversary weekend when hundreds of visitors are in town for the Marton Country Music Festival.
Chief executive Ross McNeil said a process error at the plant earlier in the week resulted in discoloured water but it has remained safe to drink throughout.
"I'm confident that Marton water will be running clear by the weekend and we apologise to residents and business operators that have been affected," he said.
"If you have clothing or other material that has been stained by discoloured water, we ask that you contact us, as well as your insurer, as we may be able to help."
Staff have been flushing pipes around Marton and residents are being asked to run their taps, especially hot taps, to clear discoloured water.