The 25-year-old singer - who has reverted back to her natural brunette locks after a stint as a redhead - explained she bought a box of dye from a British supermarket chain because she "couldn`t be bothered" to maintain her bright locks.
She said: "I bought a box of brunette hair dye from Tesco for £1.86 and coloured it myself at home. It was a lot of upkeep and I couldn`t be bothered to maintain such a distinctive colour.
"I don`t need to go to fancy hair salons. It was no big deal for me to stand over a sink at home and do it myself."
Charlotte - who has two children, Ruby, three, and two-year-old Dexter, with ex-boyfriend Gavin Henson - admitted while she received a lot of criticism about her bold former hairstyle looking "common", she was a fan of her stand-out look.
She added to the Daily Mail newspaper: "I know lots of people said my bright red hair made me look washed out and common - but I liked it."