The victim had been walking at Harlaw Reservoir, near Balerno, when he was struck in the face with a Buckfast bottle.
He spent four nights in hospital where he underwent gruelling facial surgery – including a complex operation which involved part of his nose being re-attached.
The 46-year-old, who does not want to be named for fear of reprisals, approached two men near the reservoir as he thought he recognised one of them through his work.
When he realised he did not know him, he apologised for the misunderstanding and carried on his way – but minutes later, he was hit in the face by a bottle.
The victim said: “I had only been back from holiday for about two hours. I had just been walking my dog and walking around and I thought I recognised the guy. His friend was being really rowdy. I just walked away, and my dog had walked into the woods.
“I was shouting for the dog and when I turned round, a guy smashed me on the head with a bottle.”
He is not sure if he was knocked unconscious, but says he cannot remember very much after the incident, which happened at around 9pm on Friday night.
The man is now so traumatised by the painful attack that he is nervous about returning to the reservoir.
After spending Friday night in Edinburgh Royal Infirmary, he was transferred to St John’s Hospital in Livingston for maxillofacial surgery.
His wounds were so severe that he had to have an operation to re-attach his nostril, requiring extensive work on his septum.
He also had to have stitches on his forehead and on a large cut at the top of his nose.
The victim was discharged from hospital yesterday following an operation on Monday evening.
His surgeon has warned that it is too early to say how well the scars will heal.
“There was a lot of damage from one impact,” the victim told the News last night. “I think I might have been knocked out. I had been in such a good mood, as I’d just got back from my holidays. I walk there twice a day – but I don’t think I’ll go there again.
“I’ve gone there all my life. I didn’t expect that to happen.”
The victim, who lives in west Edinburgh, is self-employed and will be off work for at least the rest of this week, having a knock-on effect on his earnings.
He said he had noticed a rise in antisocial behaviour around Harlaw Reservoir during the better weather, with large groups of youngsters congregating at the popular beauty spot.
He believes this is having a negative impact on walkers and anglers who fish at the Harlaw and Threipmuir reservoirs at the foot of the Pentland hills.
“It’s ridiculous, there are fires every night,” he said. “People have been camping up there.”
Edinburgh City Council, which manages the Pentlands Regional Park, said it had not received any recent reports of antisocial behaviour. It is understood that a man has been arrested and charged in connection with the incident. However the senior investigating police officer was unavailable for comment last night.