Apparatus for preparing beverages comprising a module (10) for distributing a beverage by supplying a pressurised liquid, a liquid supply tank (7), gas supply means (65) configured to supply the module with pressurised liquid, a liquid feed chamber (80), the said chamber being arranged, in a filling configuration, to communicate with the tank (7) in order to be filled with liquid and the said chamber being arranged, in a module supply configuration, to communicate with the gas supply means in order to pressurise the liquid in the chamber and to distribute a quantity of liquid under a certain pressure through the module. Preferably, the chamber (80) is bounded by at least one elastic wall (85), separating the gas from the liquid in a sealed manner and, configured to deform elastically and thereby reduce the internal volume of the chamber under the effect of the gas thrust against this wall. The invention applies, for example, to mobile or portable coffee or multi-beverage machines.