Karen Bailey spotted the shell when she bought her home in Kingswood village, Gloucestershire. A friend, who collects military shells, informed her that it was safe to keep.
However, when a contractor helping her with the renovation noticed it, he insisted she should call the police.
A police officer went to collect the shell and drove to the police station with it in the boot of his car. He was then ordered to drive it back to its original spot.
Bomb disposal experts from the Royal Logistic Corps arrived later to safely remove the bomb, as well as evacuate six families from the area.
Bailey told Metro: "I didn't know they had closed the road until somebody told me about it the next day.
"They were willing to risk a young man's life. They should have redirected the bomb squad to the police station rather than take it back and evacuate everybody."
Gloucestershire Police stated they did not believe the device to be dangerous on first inspection, though admitted afterwards: "On further analysis, we believed it could have been a risk to the public."