Residents in the two townships have been under a boil water notice since February 12 after a local water reservoir was found to be contaminated.
"In most cases people living, working and visiting in Akaroa and Takamātua no longer need to boil tap water - it is safe to drink again without boiling," said Christchurch City Council Council head of three waters and waste Helen Beaumont.
"However, if your property has a drinking-water storage tank connected to the water supply network, then you must keep boiling your tap water.
"There is a chance your storage tank still holds potentially contaminated water from the old reservoir and it needs to be properly cleaned before it can be considered safe."
The city council want to hear from anyone in Akaroa or Takamātua with a drinking-water storage tank connected to the water supply network. Residents can email or phone 0800 800 169 to leave their contact details so council staff can follow up with them directly.
"The streams that supply drinking water to these townships are critically low, with rain forecasts suggesting they will remain very low for a number of weeks yet.
"We need Akaroa, Takamātua and Duvauchelle residents to be especially mindful of their water use at this time.
"Please take steps now to actively reduce the amount of water you are using around the home, otherwise there is a strong possibility of water interruptions or shortages over the coming weeks – the situation is that serious.”
Under the level 4 restrictions, hand-held hoses, unattended hoses, sprinklers, and garden irrigation systems are not allowed. Using water to fill pools or paddling pools is also not allowed.
Gardens can still be watered by collecting indoor water already used for washing vegetables, dishwashing or bathing.
