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When water travels via pipes, some energy is lost due to friction which is termed as head loss. In simpler language, you lose energy when riding a bike uphill because you’re fighting gravity. Similarly, when water moves through the pipe walls, there’s a water loss caused by friction of that movement leading to head loss. And to make sure that the water reaches at the right place, efficient water conservation systems are designed. Thus, head loss in water distribution plays a significant role. 

Before we proceed, let's dive deeper into understanding head loss, the causes of head loss, its importance, practical solutions for eliminating head loss, importance of head loss, and so much more. 

What is Head Loss?

Head Loss
Image Source: Freepik

In layman's terms, the head loss is the total of the pressure loss that a fluid sustains from one suction point to the discharge point. The cause of head loss is the lost momentum when the liquid flows and this depends on the pipe diameter, fluid viscosity, pipe length and accessories such as elbows and valves within the pipework. Also known as pressure loss, the head loss is responsible for reducing the total head i.e. the sum of velocity head, potential head and pressure head which is caused due to the friction in the fluid’s motion.

Simply put, head loss is the energy required to overcome the friction caused by the pipe walls or other technological equipment. Head loss is defined as the loss of energy but it does not mean the loss of fluid’s total energy because the total energy of the fluid is conserved due to the law of conservation.

Classification of Head Loss

Pressure loss or head loss is caused when anything is introduced in the path of the fluid. That’s why it's crucial to work out the head loss that will be incurred within the installation to determine the pressure required to pump to operate efficiently. 

There are two major categories of Hydraulic system head loss:

  • Minor head loss that occurs in the pipes due to elbows, joints, valves, etc. These are a function of flow velocity, flow regime and the geometry of a given component. For all the minor losses in the turbulent flow, the head loss varies as velocity squared. These losses are more important than the major losses, that’s why it is essential to find a convenient method of expressing the minor losses in the flow with the help of a loss coefficient (k). 
  • Popularly known as friction loss, major head loss happens due to the friction in straight pipes. These are a function of flow velocity, flow regime, and friction factor along with pipe diameter and length. Being caused by frictional resistance, there’s a gradual decrease in the fluid’s energy as it moves within the conduit. Major head loss is important for analyzing and designing fluid flow systems to minimize energy loss and ensure efficient water operations.

Darcy-Weisbach Equation

The Darcy-Weisbach equation is a simple formula that helps understand the energy loss due to friction when the water flows through pipes. It is a comprehensive guide for the engineers, used for designing water systems. This water loss is a huge loss especially in the pipes that are moving faster. With the help of this equation, engineers can figure out the best pipe shape and size to make sure that the water flows smoothly while minimizing the energy loss. 

Let us understand it with an example. Imagine you’re pushing a ball on a rough floor. The harder you push the ball through the wall, the more energy will be lost. The harder push here depicts a faster flow while the rough floor represents the pipe walls. The Darcy-Weisbach equation helps engineers understand that this energy loss depends on the speed, length and size of the pipe and water flow.

In short, the formula is designed to save money and resources by designing effective water systems for head loss.

How to Calculate Head Loss?

Do you know that head loss is calculated taking into consideration ‘The Darcy-Weisbach’ equation which is considered one of the most flexible head loss equations for a pipe segment? It is represented with the help of the following formula:

Δpmajor_loss = λ (l / dh) (ρf v2 / 2)

The representation of various symbols is described in a tabular form below:


Darcy-Weisbach friction coefficient 


Hydraulic diameter of the pipe 


Length of the pipe 


Head loss or fiction loss


Fluid density

Velocity of the water

In common parlance, calculating head loss in fluid dynamics means you need to understand how much energy water loses while it flows through the pipes and for this you need to collect all the information like the length, diameter, flow rate of the water and other properties of water like viscosity. 

Explaining Darcy-Weisbach equation with a simpler example:

Let’s say you have a garden hose and you want to know how much water is lost during the water flow within the hose walls. The length of the hose is 10 meters, diameter is 0.02 meters, friction factor is 0.04 and the water is flowing at a velocity of 1m/second. Now, putting this in the Darcy-Weisbach equation, you’ll get the head loss around 2.04 meters approximately. 

How Head Loss can be Reduced?

Head loss can be reduced by using smooth pipes i.e. the pipes made of smoother materials and keeping them clean to reduce the water loss. Another thing to keep in mind is the size of the pipe because if the size is too huge, it would lead to unnecessary head loss. Selecting the right size of pipe for that particular amount of water ensures that water flows efficiently without any wastage. Keeping the pipes straight is another factor that helps in eliminating head loss because pipes with lots of turns and bends make it harder for the water to flow. 

Most importantly, always mind the pressure in the pipes because if it’s too much, there would be a large amount of head loss. By controlling the pipe’s pressure, companies ensure that water flows at the right speed, therefore minimizing the head loss in the pipeline. Fixing leaks is another crucial step to reduce head loss because that makes sure that the water does not escape from the cracks and holes.

Last but not the least, using smart and advanced technology like Dhaara Smart and Live from Kritsnam for minimizing head loss in real-time by optimizing the systems. 

Head Loss vs Flow Rate

Let’s break it down into simpler terms:

  • Head loss is the energy that the water loses during movement through the pipes
  • Flow rate is the rate at which the water moves through the pipes. For example, when water in the river flows fast that is termed as a high flow rate and vice versa. Flow rate determines how quickly the water flows through the pipes.

The thing is both of them are related in a way that when flow rate goes up, the head loss also increases. Both are two sides of the same coin as one goes up the other goes up too. 

Say Goodbye To Head Loss With Kritsnam!

UN-Water states that the impacts of climate change are first seen through water posing a direct threat to businesses they operate in. This being said, it’s important for the businesses to become water secure as it affects the corporate financial performance worldwide. Therefore, the practical solutions for head loss is staying cost-effective by implementing a bespoke water conservation system - Kritsnam.

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