A swimming alert has been issued for Auckland's St Mary's Bay, as Watercare monitors the discharge from the Sky City fire

Initial tests suggest the water in the basement of the new convention centre, is clear enough to head into the wastewater system and out to sea.

Watercare says it will be released into the network at a rate of 25 litres per second.

Last night, Watercare issued the alert for St Mary's Bay as a precautionary measure, saying some water from the basement had been pumped into the stormwater system.

However, this morning Fire and Emergency told Newstalk ZB the water was still all contained in the basement, and they won't start pumping it out until they have confirmed test results.