How Does Water Pressure and Flow Work?

How does water pressure and flow work? If you have ever set foot in a home that does not have running water, or even if you are merely searching for the nearest bathroom sink, then it is likely that you have been exposed to an argument about the source of that faucet-or the direction that water flows. This debate has roots that go far back into early American history, but the recent advent of better plumbing techniques and materials has combined with the need to conserve and have people pay more attention to their water usage.

The basic premise behind the question is whether or not piping is responsible for the amount of pressure that is exerted on a pipe. While some sources of water are naturally higher than others, pipes placed strategically in the right locations can create more than enough pressure to properly move any liquid through them. The only real question then becomes how the pressure and volume of water exert itself on the pipe. A good example of this is a kitchen sink. The sheer volume of liquid that passes through the sink will cause significant pressure. To a lesser extent, even the movement of objects in a moving stream of water will cause similar effects.

A simple way to visualize this concept is to imagine the average stream of water exerting its force in one direction. Any pipe that is inserted into such a pipe will be pulling the water in that direction. If the pipe were simply placed in the middle of a lake, then the effect would be the same, but with the added pressure of the lake in the opposite direction of the pipe. Obviously, the pipe cannot possibly be sitting in the center of the lake in an unsteady way. In order to demonstrate the difference between pipe placement and water flow, it is necessary to have a fixed measurement of the height of the water table, the width of the pipe, and the direction in which the pipe will be inserted.

When we talk about pressure and flow, we must also talk about gravity. This is commonly known as the upstream pressure, and is the force of the downward pull of water against the stream of gravity. In a given stream, the pressure exerted by upstream water equals the weight of the downstream water. To put it differently, if the upstream stream exerted more pressure than the downstream stream, then the downstream stream would experience a drop in its upstream pressure. Understanding this law of gravity is crucial to understanding how does water pressure and flow work.

How does pressure and flow work when the pipe is inserted into a bend in the stream? In a given area, where the curve of the water’s path through the pipe is acute, the downstream stream will experience a force of downstream pressure equal to the force of upstream pressure exerted on it. At points along the bend in the pipe, however, the opposite is true. Points along the pipe that are too shallow will experience no downward pressure, while areas where the bend is too steep will experience a force of upstream pressure equal to the sum of upstream and downstream pressures experienced at those points.

How does water and its accompanying pressure to move through a pipe? The pipe that is bent works like a hose; water is forced to go uphill because of the downward pressure on the pipe, while the reverse is true for a pipe that is straight. The amount of pipe and how much pressure is exerted depends largely on the pipe material (i.e., what comprise the pipe), the orientation of the pipe to the source of water, and the diameter and length of the pipe. Understanding how does water pressure and flow work is important in the construction of residential and commercial plumbing systems.