The centre is open for business at the premises, in Priory Road, but visitors are being directed to use two other pools inside the building until repairs are carried out to the affected internal window.
Facilities manager Rhys Collins said: "We had a glass panel shatter a couple of days ago. One of our managers arrived on Friday morning to find that a panel had shattered. It wasn't due to any sort of vandalism, but we're not sure what caused it.
"The pool will reopen as soon as we can get the remedial work done.
"We have four pools here and over the Christmas bank holiday period we only tend to open two of them anyway, so the centre is still open and people are still coming in to swim."
He said no one was in the building when the glass fell.
In July 2016, Shropshire Council approved proposals for the facilities to be relocated to Shrewsbury Sports Village, in Sundorne, as the preferred location for a new pool, unless the community groups come up with a successful plan to save it.
More than 30 people took part in protests against the recommendation to build a new out of town leisure centre. The decision followed a two-year review.
Shrewsbury Town Council, Shrewsbury's Business Improvement District, and The Quarry Swimming and Fitness Forum said they were concerned that moving the pool would harm Shrewsbury's town centre.