A system includes: a water reservoir configured to store water; a brew chamber extending below and contiguous with the water reservoir; a piston configured to run in the brew chamber, defining a base of the water reservoir, defining a port extending between the water reservoir and the brew chamber, and including a valve coupled to the fill port and operable in a) a closed position during downward advancement of the piston and b) an open position during upward retraction of the piston; a heating element configured to heat water occupying the brew assembly; and an actuator configured to retract the piston to transfer water from the water reservoir, through piston via the port, and into the brew chamber and to advance the piston by a target piston travel distance—corresponding to a piston swept volume that yields a target brew volume—to displace liquid from the brew chamber.