A beverage forming method and system in which a waste bin arranged to collect leaked or spilled liquid has a liquid level sensor and can be removed from the beverage forming machine, e.g., to allow disposal of the waste bin contents. One or more electrical contacts on the waste bin can be connected to the level sensor and electrically connect to control circuitry of the beverage forming machine when the waste bin is received by the machine. A liquid level detected by the level sensor may correspond to a fill level that is far less than the maximum volume of the waste bin, allowing beverage production to be prevented unless the waste bin can collect the full volume of a beverage dispensed.