How Does A Pool Pump Work?

If you look after a pool regularly, you may have picked up a bit of knowledge in the process.

After a while, certain tasks become easier, like cleaning away debris or testing chlorine and pH levels. While pool maintenance becomes routine, you may have looked at the pool pump only to realize that you don’t know how it works.

As you use your pool pump daily, it’s a good idea to become familiar with its setup. You’ll know how to keep your pump in optimal condition, saving yourself some money in the process.

If you’ve ever wondered how a pool pump works, we’ll cover the answer in this article, as well as what each component does within a pump. Keep reading to find out more.

How Your Pool Pump Works - The Basics

If you’re not interested in a lengthy answer, here are the basics of how a pool pump works. You need a pool pump to pass water through the larger circulation system. It uses energy to direct pool water into the pump and filter, then into the pool again.

A pool pump will also move water through any extra features, like a heater or water feature.

As long as your pump is working properly, it will repeat this procedure a few times each day. Pools vary in size and may have specific needs, so pool pumps differ with how much power they need and how quickly they can run.

The pump is important, as it acts as the heart of the pool’s circulatory system. Without it, the pool water won’t be clean or safe to swim in. This is why your pump needs to run regularly.

It isn’t a good idea to stop running it, even for a couple of days, as dirt and harmful bacteria can build up and cause issues. Your pool pump should have a recommended amount of time that it needs to run for, so as long as you do so, you shouldn’t have any problems.

How Does A Pool Pump Actually Work?

We’ve covered the basics, but now we’ll get into the longer answer. Pool pumps are sometimes called ‘centrifugal pumps’. This is because they rely on centrifugal force, as they direct water away from the central force.

Water enters through the pump's inlet and leaves through the outlet. A pump will also have an electric motor on one half, and a hydraulic wet end on the other. The electric motor generates power. Water progresses through the pump via the wet end before it moves towards the filter.

Energy from the electric motor transforms into movement as the motor energizes the impeller. The impeller looks like the blades of a blender. As it is charged, it rotates another part named the volute. The volute links to the wet end, moving the water at high speed in the direction of the impeller’s outer rim.

This process of the water moving acts as a centrifugal force, which makes a vacuum, a space where negative pressure occurs. A vacuum is needed to seal the pump. If the pump wasn’t sealed, it would move air along with the water.

As the volute spins, it creates energy, changing its speed so that water moves out of the pump.

Parts Of A Pool Pump

We’ve covered how different parts work within a pool pump, but we’ll further get into what each component does below.

Pump Motor

The pump motor has many different parts inside it. Within the motor is a motor shaft. This is a thin piece of metal that protrudes from the motor, linking and rotating the impeller.

If you open the pump motor, you’ll find metal brackets that reinforce the bearings inside. These brackets are called end bells, but they’re also known as cover plates or end shields.

The bearings are needed so that the motor can rotate easily. They’re located inside a sheath known as a bearing shield. If the bearings break down, the pump can overheat.

Other than linking to the impeller, the motor shaft is needed to join with the internal rotor, which energizes the actual shaft.


The impeller is the most vital part of the pool pump. This is the only part that moves, used to push the water forward at a high speed.

Impellers come in two types. Semi-open face impellers are normally found in older pumps. They don’t work as well as closed-face ones.

Newer pumps tend to have closed-face impellers, as they are better for lifting and supplying the pool with enough water. Closed face impellers also have a greater flow rate, as they can propel up to 50% more water than semi-open ones.

Pump Seal

A pump seal is used to stop water from leaking out of the pump’s motor shaft. This is found near the motor shaft.

The seal needs water to keep it cool and is spring-loaded to compensate for alignment failures. Out of the parts within a pool pump, pump seals are one of the most requested replacement parts. 

If your pool pump doesn’t have an effective seal, it might begin propelling air along with water. This can overwork the motor and make it run hot.

Pump Basket

The pump basket holds any debris from the water flowing through it. It’s shaped like a basket with a grid at the base. The water passes through the holes but the grid prevents any leaves, twigs, or dirt from getting to the filter.

Pump Housing and Strainer

The pump basket lies within the pump housing and strainer. Water passes through here, while a rubber seal stops air flowing toward the pump.

Pool Pump and Pool Circulation System

We’ve gone a bit more into what each pool pump component does, but how does the whole thing work within the larger circulation system?

The pool pump begins to take in pool water once it passes through the skimmer. The skimmer is a rectangular shape on the edge of the pool, though some pools may have several around their sides.

They also have baskets on them to trap debris. As long as pool water rises halfway along the skimmer, it should take in enough water.

After it flows through the skimmer, water passes through the actual pump. Another basket contains any extra debris within the housing. Water is then propelled through to the filter pump, which removes any smaller debris that’s naked to the eye.

If your pool has any extra features, like heaters or waterfalls, water passes through these, then flows back into the pool. The pool water remains clear and free from debris.