The present invention relates, amongst other things, to a flushing system (40) for flushing an energy source device (15) and/or an energy sink device (16) of an energy system (10), the flushing system comprising: a flushing device (41) having a storage chamber (45), which on the input side is fluidically connected to a first line portion (46), which is formed as a flushing line starting from the energy source device (15), and/or to a second line portion (47), which is formed as a flushing line starting from the energy sink device (16); a first monitoring device (50) for monitoring the state of the storage chamber (45), the first monitoring device (50) comprising at least one sensor device (50a) associated with the storage chamber (45) for monitoring the fill level of the storage chamber (45); and also optionally a compensation container device (54) fluidically connected to the storage chamber (45). In order to further advantageously modify the flushing system (40) by simple structural and economical measures so that the flushing system can be monitored in a safety-related manner, the flushing system (40) comprises a safety control device (53); the sensor device (50a) for monitoring the fill level of the storage chamber (45) is connected to the safety control device (53) via an interface (80, 81) associated with the storage chamber; and the flushing system (40) optionally has at least one further monitoring device (66, 70) for monitoring the state of the compensation container device (54) and/or for monitoring valve devices (48, 49, 57, 59) which is/are connected to the safety control device (53) via interfaces associated with the compensation container device and/or valve devices.