The People tracked the 46-year-old's visits to the White Lion pub, which is located near the ITV soap's set, over a period of three weeks.
The publication revealed that Charles, who worked to beat a booze and drugs addiction after being snapped smoking crack cocaine in 2007, downed drinks at the establishment four days in a row last week, while another troubling session began as early as 11am.
During the short period, Charles made trips to the White Lion before, after and between shooting scenes for Coronation Street.
A friend of the actor stated: "Craig is becoming known for his boozy lunches, and people are beginning to worry.
"It is known he is often in the pub and it's not a good environment for him. He himself admitted it was his love of alcohol which led to his downward spiral into drug addiction. It can't be good for him leaving work at just 11am and heading straight for the pub and getting stuck into the booze."
A Coronation Street source added: "Craig was supposed to have cut back on the drink and that's what he would like people to think, but the truth is he is back on it. It was the only the other day that he was joking to the crew that he had a monumental hangover.
"He can certainly handle his drink. But people do find it worrying that he is back on the booze given his past. We would all hate to see history repeat itself."
Charles previously sparked fears about a return to his old ways after he was spotted looking dishevelled at a Cheshire pub in 2008.