The change meant a quantity of naturally-occurring manganese, which was not present in the upper level of the dam, entered the treatment plant and discoloured the water that was supplied to some households.
"We had residents contacting our call centre on Friday and over the weekend," Mr Edmondson said.
"We apologise to our customers and would like to reassure them that the water, which is now showing no discoloration, was and continues to be safe to drink."
Tests showed the manganese levels in water samples taken from the supply were below maximum acceptable values (MAVs) set by the Ministry of Health.
Kerikeri local Jeremy Sullivan posted photos to the Northern Advocate Facebook page showing the colour of the brown water against the contrast of the white bathtub.
Mr Sullivan said they were told the water would clear in 24 hours.