A tissue dispenser, a method, system, and a sensor unit for detecting level of a consumable tissue product (201, 301) in a tissue dispenser (103, 106) located in a washroom. This includes provided a sensor unit utilizing two sensor elements (420, 430) each arranged to measure light reflected from a reflection field located on the tissue product, reflected directly from the tissue product, or measure the absence of the tissue product. Data from the sensor elements are wirelessly transmitted to a server (901) for further handling, such as for instance notification to a janitor in charge of service of the washroom.