The notice was first put in place for the district close to two weeks ago.
Affected areas include: Greymouth, Cobden, Blaketown, Boddytown, Karoro, South Beach, Paroa, Kaiata, Dobson, Taylorville, Stillwater, Runanga, Dunollie, Coal Creek & Rapahoe.
The Grey District Council said it was holding discussions with water regulator Taumata Arowai, after receiving additional direction on what had to be done before the boil water notice could be lifted.
It needed to satisfy the regulator's direction, in addition to the three clear days of testing, before the notice could be lifted.
Samples have been clear since last Thursday and there has been no reported sickness.
Grey District Council chief executive Joanne Soderlund said the council understood the magnitude of the Boil Water Notice on businesses, organisations, and the community.
"We sincerely apologise for the disruption this has caused for all. We are working tirelessly to ensure the water supply is safe and to resolve this issue as quickly and thoroughly as possible," she said.
The NZ Food Network has been donating bottled water to the district, which would be distributed this week to communities around greater Greymouth.
The council said the problem could be linked to a broken pipe, or a backflow issue.
