In a method for determining a filling level (F) of waste water (8) in a tank (6) of a vehicle (2), wherein a respective flushing quantity (P) of waste water (8) is fed to the tank (6) by means of flushing processes, a binary filling signal (La-e) (waste water (8) present or not) is determined at at least two measuring positions (20a-e) at the tank (6) with known filling quantities (Ma-e), the filling level (F) is determined as a sum of a basic filling quantity (B) and an inflow quantity (Z), wherein the basic filling quantity (B) is selected as zero or as the greatest filling quantities (Ma-e) of active filling signals (La-e) at a starting time (A), and the inflow quantity (Z) is determined as a sum of all the fed-in flushing quantities (P) from the starting time (A).
A measuring arrangement (12) for determining the filling level (F) contains an evaluation module (14) with an interface (16) for the flushing signals (S), and at least two sensors (18a-e) for the filling signals (La-e), wherein the evaluation module (14) is designed to determine the filling level (F) according to the method according to the invention.
A waste water arrangement (4) with the tank (6) and at least one flushing device (10) contains a measuring arrangement (12) according to the invention.