This verse suggests that there are degrees of impurity depending on what a person does in the unclean house. If someone merely enters the house, they will be unclean until the evening. If a person eats or lies down in the house, the level of impurity is more severe.
47 Celui qui aura couché dans la maison lavera ses vêtements. Celui qui aura mangé dans la maison lavera aussi ses vêtements.