I'm looking at googles mocktails maker. And it puts 2 holes in a container. 1 hole is connected to a pump that will take water out and the other connects to a backflow prevention valve that only allows air in and not liquid.
What is the point of having that valve? It doesn't connect to anything. Also when I test it with and without having that valve the water does the exact same thing.
EDIT: Does it have to do with keeping the container pressurized? Why would I need to have a constant pressure if the pump doesn't require it.