The City of St. John's has issued a news release telling residents in the city and several surrounding towns to only run their taps for emergencies.
The neighbourhood of Kilbride briefly lost all water on Thursday evening after a pump broke down for several hours.
Jennifer Mills, a spokeswoman for the city, says 15 electrical contractors are working at the site of the Bay Bulls Big Pond water treatment plant in an attempt to restore its power.
Mills said late Thursday that it was "critical" residents cease using water for washing dishes, laundry and bathing.
The rationing applies to residents of the City of St. John's, Mount Pearl, Conception Bay South, Paradise and Portugal Cove-St. Philips.
The city has also contacted commercial water users and asked them to discontinue operations until the treatment plant is back in operation.
The city says one employee of a contractor at the plant was injured during the fire at the treatment plant and the worker had been transported to hospital.