Water could be seen streaming from the brickwork outside the Wilko outlet, facing North Street, at midday today.
The shopping centre remains open, but Wilko has been closed and the centre’s elevators have been shut down, with staff clearing up large puddles of water on the first floor.
Shopping centre staff were making alterations to the sprinkler system when a fault released the deluge of water, according to Rob Fryer, the centre’s manager.
He said: ‘We were doing some sprinkler system modification for the new Citizens Advice Bureau unit, and the valve failed and let loads of water in the building.
‘We believe it was a faulty part.
‘We’re on disaster recovery and clearing up – we didn’t need this on a Monday morning.’
The shopping centre is hoping to reopen the elevators and Wilko store by the end of the day.