Food waste in households is a consequence of the accumulation of improper practices employed by consumers when dealing with food. The survey estimated the impact of practices of Polish respondents, in the context of selected food safety and hygiene issues, on throwing away food due to spoilage. The survey was conducted in 2019, in a random quota-based, nationwide sample of 1115 respondents 18 years old and older. Synthetic indicators (SI) were created to assess the knowledge and practices of Polish adult respondents concerning selected areas of food management and the frequency of throwing food away. Most food products were not thrown away at all or were thrown away occasionally. Regression analysis revealed that the frequency of throwing food away was to the greatest extent related to food spoilage (β = 0.223). Among the five areas of Polish respondents’ practices covered by the analysis, the most conducive to wasting food due to spoilage were improper proceedings with food after bringing it home (β = 0.135; p = 0.000), a failure to ensure proper food storage conditions (β = 0.066; p = 0.030), or inappropriate proceedings with uneaten meals, excluding the food plate (β = 0.066; p = 0.029). To reduce food waste in Polish households, drawing the attention of consumers to the conditions of food storage at home seems appropriate. It is also vital to convince them to use freezing of uneaten food as an effective method of extending the life of food products.