The 'Lego House' hitmaker - who is currently supporting Taylor Swift on her 'Red' tour - admits he would go days without washing when he began his quest to become a musician and would be forced to sit on a London Underground train all day as he had nowhere else to go.
Speaking to the Daily Star newspaper, he said: "Sometimes when I didn't have a place to shower, I'd wait for the Tube to open up at 5am and sit on the Circle Line and go round and round. I wouldn't shower.
"I couch surfed and floor surfed sometimes. Once I was staying at this student house and had a shower but didn't have a towel.
"This lad had a Green Day poster, I literally just scraped the water off with it."
The 22-year-old singer - who has been romantically linked to Selena Gomez - claims since becoming a global star, his cleanliness has improved.
He said: "Now, I shower every day."
Ed - who has won two BRIT Awards - previously admitted he almost didn't make it into the music business because industry chiefs knocked him back for being "chubby and ginger".
He said: "Every single label I had gone to at the time had told me this song wasn't a hit. They said this song wouldn't work.
"And the fact that I was slightly chubby and ginger was not a good 'marketing tool' for them."