An automated beverage brewing system includes a liquid storage tank and a metering chamber. The metering chamber is at least partially submerged beneath a standing level of liquid in the storage tank. The chamber includes a sealable liquid inlet port communicating with the interior of the storage tank beneath the standing level of liquid. The chamber also includes a liquid outlet port and an aperture that receives compressed air, wherein the compressed air forces a predetermined amount of liquid from the liquid output port of the chamber for use in preparing a brewed beverage. A pump provides the compressed air and a controller monitors a pressure signal value indicative of the air pressure in the metering chamber. The controller commands the pump on to commence flow of the predetermined amount of liquid from the metering chamber. The controller then commands the pump off several seconds after detecting a drop in air pressure within the chamber, indicating that the predetermined amount of liquid has been delivered to the brewing chamber. The chamber is then vented to ambient pressure, which opens the sealable liquid inlet port and refills the chamber.