Certified Landscape Irrigation Auditor

How does the length of tubing in a drip system impact pressure?

1. It does not affect pressure

2. Longer tubing always increases pressure

3. Longer tubing can reduce pressure

4. It varies based on emitter type

The correct answer is: Longer tubing can reduce pressure

In a drip irrigation system, the length of tubing significantly impacts the pressure due to factors such as friction loss and flow resistance. The longer the tubing, the greater the friction that the water must overcome as it moves through the pipes. This friction loss results from the internal surface of the tubing as well as the fluid dynamics involved when water flows over a distance. As water travels through a longer length of tubing, its pressure gradually decreases. This phenomenon is known as pressure drop, which occurs because of the resistive forces that the water encounters. Thus, longer tubing can lead to reduced pressure at the emitters, making them less efficient in delivering water to the plants—they may emit less water than intended or may have uneven distribution depending on the pressure at different points in the system. While emitter type can influence how pressure impacts water flow, the fundamental principle remains that increased tubing length results in increased friction loss and subsequently a reduction in pressure. Therefore, the relationship between tubing length and pressure is primarily characterized by the fact that longer tubing can reduce pressure in a drip irrigation system.