A Perth man who lost his leg during a gruesome jet-ski accident has told how he had to pinch his own artery in his severed limb to stay alive.

Blake Granston, 23, is still recovering in Royal Perth Hospital after the accident at the Belmont water park, near the Ascot Race Course, at 2.40pm on Tuesday last week.

"I was jet skiing in the Belmont ski area for a Christmas party for work, I got hit by another jet-ski on the side," he said.

"It came in from my left side. I didn't see it coming. I was on the water and the next thing I know I'm up in the air, then floating in the water looking at my leg in front of me."