Meanwhile, the playground project's Givealittle page, updated after the incident, had an extra $900 donated.
Lead teacher for playground redevelopment Jacque Hayman said it had been an all-round humbling experience.
"We never expected in our wildest dreams to have this outcome. We're lucky to have such a problem, it's a great problem to have."
She said the situation had restored her faith in humanity and she was glad the thief had done the right thing.
"It's a great lesson for kids, sometimes you make mistakes but you can make amends."
Eight-year-old Asher Dry, who had appealed to whoever took the slide to bring it back, was beaming.
"We're happy to have it back, it's actually quite good and quite responsible," she said.
Teacher Oliver Tattersfield said the kids had been incredibly patient and they were relieved it was over.
"Someone realised they had made a bad choice and we don't hold any bad feelings towards them."
He said they were grateful to the company who donated the slide and as far as they were concerned the return of the first slide had resolved the matter.
"We don't need to know who it was, hopefully they feel good about bringing it back."
The school was considering their options now they had two slides to install, and had asked the kids what they would like to see done with the second slide.
Asher's vote was on a waterslide.