Nuns used pliers to pull out the teeth of a child sex abuse victim at a Ballarat orphanage, and he was also locked in a dungeon known as the "horror room" and abused by a priest, an inquiry has heard.

Giving evidence at the Royal Commission into Institutional Responses to Child Sexual Abuse, Gordon Hill - now in his 70s - said he was taken to the St Joseph's Home as a three-year-old.

He told the inquiry he could still remember "all the little kids getting on the bus" in 1946.

WARNING: this story contains material which may be disturbing for some readers.

Mr Hill said he was among a group at the home known as "the Drones", children who had no-one and instead of going to school were put to work.

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He said he was assigned a number and a locker number, instead of a name, and did not know his own surname until he was 10 years old.

Mr Hill told the inquiry he was first abused by a priest at age five, in a dungeon-like environment he called "the horror rooms".

"I was given a drink ... I blacked out," he said.

"When I woke up my genitals and bottom hurt ... I discovered bite marks. The priest told me to get out."

Mr Hill said a nun had told him to go to the rooms.

"Father wants to cleanse you, 29," the nuns said to him.

He said when he woke up and walked outside, "The nun was laughing. Big joke to her ... she told me to get back to work. Maybe because I was walking funny."

On other occasions Mr Hill said he was strapped down naked, tied up and sexually abused.

"Sometimes the nuns would punish us by pulling out a tooth with a pair of pliers or hitting one of us in the head with an engineer's hammer."

Mr Hill told the inquiry his mouth was so sore after having his teeth removed he could not eat, so he fed his food to a mouse he made a pet of in the dungeon.

He said sticks were broken across his back and he still bears the scars.

"I made a mess on the floor because I was bleeding so much ... I was left in a room with a bucket behind a soundproof door. For a bed I had a concrete slab," he said.

"I stayed there about a month. The nuns told me nobody wants you, nobody cares about you. You're just a nobody."

Mr Hill also described being tortured with electric shock therapy while he was tied down, with pads on his head and neck, and a catheter inserted 'so I didn't make a mess'."

He said his hair on the back of his head never grew back from where it bounced against the bed.

"Sometimes I think, how the hell did I survive all that happened to me?" he said.

Mr Hill began crying as he recalled the ongoing nightmares and toll the abuse had taken on his life.

"I felt like an outcast, always in the background, from all the rejection I got when I was at St Joseph's," he said.

"One of the last things my wife said before she died ... was that she hoped one day I could tell my story."

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Mr Hill told the commission someone had to pay.

"The Catholic Church should be turned upside down," he said.

He added: "It's time they came out from behind the robe and repaid the poor. I want to make sure that kids who are sexually abused are not forgotten anymore."

Mr Hill said the Victorian Government should also pay because its inspectors failed so many children.

He said a full study should be conducted on how many lives had been lost to drugs, abuse and suicide, as a result of the abuse.

"I bet they haven't [done one]," he said.

"They would run out of paper."

Mr Hill said he planned to stay on at the hearing today and for the coming weeks, to support other survivors.

The hearing continues.