A water pump for bottles is
a device for conveniently drawing water from 19-liter bottles. It can be mechanical (you press a button to pump water, which requires effort) or battery/electric (powered by batteries or mains electricity, pumps water automatically). They are simply installed on the neck of the bottle (the cap is removed, the pump tube is inserted, and secured) and allow you to easily pour water into a glass or teapot. Various models are available in terms of design, functionality, and price. 
Main types and appearance (photo):

    Mechanical pumps: A simple device with a lever or button, usually plastic, brightly colored (blue, light blue, gray), with a tube that goes inside the bottle.
    Electric pumps: A more modern type, often with a stand, spout, and backlight, powered by mains or battery. They look like compact coolers without a tank and come in different colors (white, black, wood-effect).