Chamindu Amarsinghe was cleaning toilets in the Channel Nine studios in Melbourne when he discovered a sanitary bin filled with $50 and $100 notes.
"There was too much to count, I thought someone was playing a prank on me," said Mr Amarsinghe, who stumbled upon the loot in August 2011.
"But when I touched the notes - all yellow and green - I realised it was real money."
He said he called his supervisor immediately, who then contacted the police. A plumber was able to retrieve more than $100,000 from the toilet, with about $1200 pulled from the pipes.
As no-one has come forward to claim the cash, a magistrate ruled this week that Mr Amarsingh will keep $81,597 of the loot because of his honesty. The other $19,500 will go to the state.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
On Tuesday, magistrate Michael Smith said: "There's no reason why such honesty should go unrewarded".
Detective Senior Constable Daniel Thorne, who was part of the investigation, told the Herald-Sun he agreed with the decision.
"All the guys in the office felt the same. He’s a struggling student who straight-up didn’t even think of pocketing it," Senior Constable Thorne said.
When Mr Amarsinghe, who is now studying IT in New Zealand, received a phone call about the good news, he said he was speechless.
"I just want to spend my life in a normal way, find a job in IT and carry out that dream."
