The actor, who plays Ken Barlow in the ITV1 soap, was struck down with the disease as he approaches his 80th birthday, following a speaking tour of Canada.
He has spent the last few days recovering at his Cheshire home and plans to celebrate his landmark birthday with a party on Wednesday (April 25), The People reports.
"Everyone was concerned for him but he's such a battler and he never lets anything get a hold of him," a source said.
"Pneumonia can be a killer for older people but Bill has always taken care of his health and well-being and that's why he's in such remarkable shape.
"He's planning a party to celebrate his 80th birthday and wild horses wouldn't keep him away from that. He can't wait to be with his family and friends."
Roache met Canada's PM Stephen Harper, who is a huge fan of Corrie, during his visit to the country.
"Bill is currently at home recovering from pneumonia. It isn't ideal, especially with his 80th birthday coming up. But he is doing very well and feeling much better now," a spokeswoman added.