Method for controlling a discharge pump of a household appliance, comprising the following steps: starting a single-phase permanent magnet synchronous electric motor that actuates said discharge pump until the synchronous speed is reached; driving said synchronous electric motor at normal operating speed through phase control by varying the firing angle (α), wherein said firing angle (α) determines the delay in switching on a static switch, intended to cut the current supplied by an A.C. electric grid and directed to windings of the synchronous electric motor, with respect to the change of sign of the grid voltage, the static switch being switched off as the waveform of the current supplied by the A.C. electric grid is back to zero, so that the function of the phase current fed to the electric motor has a zero-current plateau, set by the closing of the static switch, spanning from the point in which the waveform of the current supplied by the A.C. electric grid is back to zero to the next switching on of the static switch; wherein, in driving said synchronous motor at steady state through phase control, said firing angle (α) is feedback controlled to cancel the phase difference between the mid-point of said zero current plateau, and the zero-crossing point of a counter electromotive force signal (fcem) relative to the same phase; characterised in that, in feedback controlling the firing angle (α) the synchronous electric motor is switched off, so that it needs to be started up again, if the required firing angle (α) exceeds a maximum threshold (α lim), where exceeding said maximum threshold (α lim) indicates the operation of the discharge pump in air-water conditions. starting a single-phase permanent magnet synchronous electric motor that actuates said discharge pump until the synchronous speed is reached; driving said synchronous electric motor at normal operating speed through phase control by varying the firing angle (α), wherein said firing angle (α) determines the delay in switching on a static switch, intended to cut the current supplied by an A.C. electric grid and directed to windings of the synchronous electric motor, with respect to the change of sign of the grid voltage, the static switch being switched off as the waveform of the current supplied by the A.C. electric grid is back to zero, so that the function of the phase current fed to the electric motor has a zero-current plateau, set by the closing of the static switch, spanning from the point in which the waveform of the current supplied by the A.C. electric grid is back to zero to the next switching on of the static switch; wherein, in driving said synchronous motor at steady state through phase control, said firing angle (α) is feedback controlled to cancel the phase difference between the mid-point of said zero current plateau, and the zero-crossing point of a counter electromotive force signal (fcem) relative to the same phase; characterised in that, in feedback controlling the firing angle (α) the synchronous electric motor is switched off, so that it needs to be started up again, if the required firing angle (α) exceeds a maximum threshold (α lim), where exceeding said maximum threshold (α lim) indicates the operation of the discharge pump in air-water conditions.