How does water travel upwards in pipes?

Water is flowing through pipes all around you, in homes and businesses, through the streets, and in more remote locations too. But how exactly does it work? It’s not hard to imagine how water can flow through a pipe that’s going downhill. Gravity can do all of the work. However, the physics of water travelling upwards in pipes or even just a pipe that’s laid flat can be a little more confusing.
The physics of water flowing through pipes can actually get fairly complex. But the basics of how water travels upwards in pipes aren’t necessarily that difficult to grasp. The basic principle is that pressure differences keep water moving, no matter which direction the pipe is going or which way the water is meant to flow. The water that enters homes and businesses from the main service lines is pressurized to keep travelling along the pipes. Some water and pipe systems may also be pressurized themselves. For example, a hot water system or central heating system might be pressurized to keep water flowing through it.
Low pressure can affect the flow of water within a system, making it more difficult for the water to flow to where it needs to be. As you can imagine, low water pressure will make it especially difficult for water to travel upwards, against gravity. However, there are always methods available for improving water pressure, such as topping up the pressure in a system and repairing leaks that may be causing a loss of pressure.