The invention relates to a combined optical container and filling level detection system (10; 310) comprising at least one removable container (14; 114; 214; 314) that has an inner space (32: 332) for receiving flowable or free-flowing media (34; 334), and at least one container receiver (12; 312) for the container (14; 114; 214; 314). According to the system, the container receiver (12; 312) is fitted with a retroreflective photoelectric sensor (22; 122; 322) and the container (14; 114; 214; 314) comprises an immersible body (36; 336a, 336b, 336c, 336d) in the form of an optical waveguide that protrudes into the medium (34; 334) and is optically coupled to the retroreflective photoelectric sensor (22; 122; 322) when the container in the container receiver (12; 312) is in a measuring position. The invention also relates to a household appliance comprising such a system.