Witch bottles are truly a part of the old tradition of participating magic, where the purpose was to harm the witch with the contents. People believed that sometimes the use of a witch bottle made the witch herself come and knock on the door while twisting in pain, ask for someone to break the bottle, and promise to break the curse.
People thought that the witch bottle was active as long as it remained hidden and intact. They made great efforts to find a good hiding place. Those hidden beneath the hearth were only found when the building was torn down or disappeared in some other way.