A man who went missing in bushland for 18 days said he made "a split decision of error" and paid the price.

Talking to 7 News, Robert Weber, 58, said he got lost near Kilkivan, west of Gympie, and went in search of water when he got lost.

He was found on Sunday, having survived off wild mushrooms and dam water for nearly three weeks.

"I made a split decision of error and paid 18 days for it," Mr Weber said.

"The first day I left it was drizzling and the dog was sleeping in the driver side. Sid was just looking, 'nah I'm not coming'. So I thought, 'all right, you stay, I'll come back with some water'.

"I had a two litre juice bottle and I never ever made it back. I could never find my way back."

Robert Weber, 58, was found after 18 days west of Gympie. Picture: 7 News
Robert Weber, 58, was found after 18 days west of Gympie. Picture: 7 News

Mr Weber said he caught sight of a rescue pilot days into the search, but could never get their attention.

Then, by coincidence, after 18 days had passed the owner of the property Mr Weber was on - Gympie MP Tony Perrett - drove past him.

"Tony, the MP, just rolled up, checking the dam, and here I was standing there going 'hello, how are you? Sorry I trespassed'," Mr Weber said.

According to Mr Weber, Mr Perrett then said: "Hello, we've been looking for you."

Asked how he felt, Mr Weber said "relief, in a grand sense".

"I never had my doubt (that he'd be found). Full stop. But there were disappointing times when the search happened and I got missed out by the boundary of it. I was looking at the pilot in the eyes and I'm going 'come on, mate, what are you doing? You're going backwards."

Originally published as The 'split decision' that cost a man 18 days lost in the wild