There is provided an aerosol generating system for heating a liquid aerosol-forming substrate. The system includes an aerosol-forming chamber, and a leakage preventer for preventing or reducing leakage of liquid aerosol condensate from the aerosol generating system. The leakage preventer may include one or more of: at least one cavity in a wall of the aerosol-forming chamber, for collecting droplets of condensed liquid aerosol-forming substrate; at least one hooked member for collecting droplets of condensed liquid aerosol-forming substrate; an impactor for disrupting airflow in the aerosol-forming chamber so as to collect liquid droplets; and a closure member for substantially sealing the aerosol-forming chamber when the aerosol generating system is not in use.