The Combine, seeing fit to both further the memory-wiping effects of Breen's Water and keep the flow of citizen Tokens/ Credits transfering between the Union and citizen's pockets, created the vending machines to allow citizens to purchase extra water at their own personal expense.
It is unknown whether the Combine have directly manufactured the vending machines following the takeover of Earth or simply converted pre-war models to the "Dr> Breen's Private Reserve" brand.
In-game, the Vending Machine can be used by simply walking up to it and pressing the action button (default "E" key), which will cause it to extract the necessary payment from your inventory and dispense a Breen's Water item into the game world.
- If the light is green, the Vending Machine is active and ready for use.
- If the light is orange, the machine has been deactivated by the Combine for whatever reason they saw fit, and will not dispense water.
- If there is no light, it is more than likely not a working entity but simply a prop, built into the map and incapable of dispensing water at any time.