A carbonation machine includes a pneumatic chamber with a movable wall. The wall moves outward to depress a pin of a gas release valve of a gas canister that is held in a canister holder of the machine when air pressure in the chamber is increased. An air release valve is closable to retain air in the chamber. An air pump is operable to pump air from the ambient atmosphere into the chamber so as to increase air pressure in the chamber. A controller is configured to close the air release valve and to operate the air pump to increase the air pressure in the chamber to move the movable wall outward to open the gas release valve of the canister to cause release of gas from the canister to carbonate a liquid, and to open the air release valve to enable the gas release valve to close.