The facility at Brow Top, which has a 24m pool and squash courts, had to been due to open to the public on Saturday.
However, because of "a small number of snagging and technical issues" relating to the learner pool, the opening date has been put back by a least a week.
The council's deputy leader, Mark Fryer, said the centre would not open until it was "pristine".
He said: "We can handle it being late but we can't handle it not being perfect. I wanted this facility to open as soon as possible but I wanted it to be pristine.
"There's a technical problem with the small pool and problems with drains which are not finished."
The opening of a new £11m leisure centre in Workington has been delayed.