Apparatus, including a carbonation chamber, is provided that includes a mixing and metering member and a gas adjustment member. The mixing and metering member is configured to respond to a fluid, including water, and an adjustable amount of gas, including CO2, and may be configured to provide a mixture of the fluid and the gas. The gas adjustment member is configured to receive the gas, including from a gas inlet, and to provide the adjustable amount of gas to the mixing and metering member, based at least partly on an adjustable axial relationship between the mixing and metering member and the gas adjustment member in order to control a desired carbonation level of the mixture.