Rowe suffered fractures to his Tibia and Fibula while on an adventure excursion for his brother's wedding "stag party".
His brother Matt is set to tie the knot with London 2012 team pursuit gold medallist, Dani King.
He underwent surgery in a Cardiff hospital and is facing a long period of recovery.
"My brother Matt is getting married and so I was away with family and friends for his ‘stag party'.
"On the first morning, we went whitewater rafting. I jumped down into the water but landed in a shallow section on my right leg."
Rowe recently helped Sky team-mate Chris Froome to his fourth Tour de France title.
"Being a bike rider you get into a lot of scrapes and you get used to injuries, but I knew straight away that it was a bad one," he said.
"It's been a big shock and I know I've got a long period of recovery ahead.
"It's early days, but speaking to the surgeon about the injury and my rehab gave me confidence so now it's a case of working towards getting myself back on the bike.
"I'm determined to get back racing as soon as I can."