The Rangitikei District Council has been using activated carbon to address odour and taste issues with its water supply.
Last week the water went discoloured and odorous with some residents describing the water as coffee-coloured and undrinkable.
Chief executive Ross McNeil said samples had been sent away to a lab and given the all clear.
"We've done the testing and they're 100 per cent happy that there aren't any nasty algal spores there," he said.
He said council staff had put it down to heavy rain and warmer weather which had stirred up the damns the water was taken from.