Life Pharmacy Rotorua owner Brett Fordyce could only stand and stare as his Central Mall store became submerged by a waterfall that poured in through the ceiling and washed out the back door.
Fordyce had gone to the store on Sunday morning and discovered a couple of ceiling tiles had fallen down and there was a little bit of water on the floor.
"I thought 'I can work with that' and started cleaning before we opened the doors," he said.
"But within minutes more ceiling tiles started peeling off the roof and then the deluge of water happened."
He said it rushed in through the top and flowed out the back "like a river".