Clutha District Council service delivery manager Jules Witt said staff were monitoring the crack, which was superficial, and the pool remained open to the public.
The Milton Centennial Pool reopened late last month after the council spent $90,000 repairing a crack in the base. Swimmers this week noticed a new crack near the first crack.
Mr Witt said it was expected the floor slab would move under the weight of the 300 tonnes of water it took to fill the pool.
There was no need for concern about the new crack as it was only superficial and did not run through the base concrete slab, he said.
Staff had closely monitored the water usage of the pool and not noticed any change since the pool reopened on February 27, he said.
A pump installed below the pool had not had to be used, suggesting there was no leakage beneath the pool.
The pool should still remain open until the end of the season.
Any repairs to the paint and crack would be done once the pool was emptied.
Clutha Mayor Bryan Cadogan said last year the repairs were only ever intended to be a temporary solution to get the pool running as soon as possible, and there was no guarantee there would be a permanent solution.
