Submersible Pump vs External Pump

Submersible Pump vs External Pump: Key Differences

Last Updated on July 23, 2023

Water supply systems rely on pumps to move water from storage to where it is needed. Regarding water pump installations, two popular options are submersible pumps and external pumps. Although both pumps are used for water pumping, they differ significantly.

Submersible pumps are installed directly in the water when considering placement and positioning, while external pumps are located outside. Also, submersible pumps are more energy efficient and quieter, but external pumps are easier to maintain and are less expensive.

Today, we’ll explore the key differences between external and submersible pumps and help you make an informed decision. Let’s discuss these pumps.

Submersible Pump vs External Pump: Key Differences Explained

Submersible Pump vs External Pump Key Differences Explained

If you’re looking for a pump for your pond or fountain, you should know the key differences between submersible and external pumps.

  • Placement and Positioning:
  • Energy Efficiency:
  • Noise Levels:
  • Maintenance and Accessibility:
  • Waterproof Seals:
  • Water Space and Tank Capacity:
  • Priming Requirement: 
  • Price:

Placement and Positioning:

The placement and positioning of a pump can greatly affect its efficiency. External pumps require a weather-safe location, while submersible pumps need to be placed inside the water tank.

Here are four key things to remember when considering the placement and positioning of your pump:

  • External pumps should be installed in a location that’s easily accessible for maintenance and repairs and protected from extreme weather conditions. It can be tricky to strike a balance, so it’s important to plan and choose a location that’s both convenient and safe.
  • Submersible pumps should be placed near the bottom of the water tank to ensure they can draw water effectively. If the pump is placed too high, it may not be able to reach the water and will run dry, potentially causing damage to the motor.
  • It’s important to consider the size of your tank when choosing a pump. If your tank is particularly large, you may need multiple submersible pumps to ensure water is circulated effectively.
  • When installing your pump, follow the manufacturer’s instructions carefully. Improper installation can lead to decreased efficiency, increased energy consumption, and even damage to the pump itself.

Energy Efficiency:

To increase the energy efficiency of your water circulation system, have you considered the type of pump and its power usage? When choosing between a submersible water pump and an external pump, the former is generally considered more energy efficient.

This is because submersible pumps are designed to solely focus on pumping water, as they are surrounded by it. As a result, they consume less power than external pumps, which need to pump and suck water.

External pumps are less energy efficient than submersible pumps because they require more power. Since they need to pump and suck water, their power consumption is slightly higher.

If you want to increase your water circulation system’s energy efficiency, you may want to consider using a submersible pump instead. Not only will it consume less power, but it will also be more effective at pumping water, which can help improve the overall performance of your system.

Noise Levels:

Hey, did you know that the noise level of your water circulation system can be influenced by the type of pump you use? If you’re considering a submersible pump and an external pump, you might want to take note of the noise levels each generates.

Submersible pumps are known for being quieter. Being submerged in water allows the water to absorb and dampen the noise generated by the pump, resulting in a quieter operation.

Conversely, external pumps can produce more noise compared to submersible pumps. This is because they are located outside the tank, and the noise may not be absorbed as effectively.

However, some external pumps are designed to operate quietly. These pumps often have noise-reducing features such as vibration-dampening materials and soundproofing enclosures.

Maintenance and Accessibility:

You don’t want to drain your tank and disassemble equipment from inside when you simply need to check and service parts outside. This is precisely the difference between a submersible pump and an external pump regarding maintenance and accessibility.

With a submersible pump, you have to go through the hassle of dismantling the pump from inside the tank, which can be time-consuming and frustrating.

In contrast, an external pump is positioned outside the tank, making it easier to access, inspect, and service without needing tank drainage or pump removal. To give a better understanding of the maintenance and accessibility differences, let’s take a look at the table below:

Maintenance and AccessibilitySubmersible PumpExternal Pump
Access and InspectionDifficultEasy
Repair and ServicingChallengingConvenient
Tank Drainage Required?YesNo
Pump Removal Required?YesNo

Waterproof Seals:

Now, let’s talk about the importance of waterproof seals regarding submersible pumps versus external pumps. Submersible pumps rely heavily on waterproof seals to maintain their integrity, but over time, these seals can corrode and potentially lead to water ingress into the motor.

On the other hand, external pumps do not require waterproof seals like submersible pumps since they are placed outside the tank. This simplifies maintenance and repair procedures, as there is no need to waterproof the motor.

This makes external pumps a more attractive option for those prioritizing ease of maintenance and accessibility. However, it’s important to note that external pumps may not be as effective in certain applications, such as those that require high pressure or constant use.

Water Space and Tank Capacity:

Water Space and Tank Capacity

Maximizing the amount of water your tank can hold is crucial, and choosing the right type of pump can make all the difference. It’s like fitting more clothes in your suitcase for a trip.

When it comes to water space and tank capacity, using an external pump is the better option. Here’s why:

  • External pumps do not occupy any space inside the tank, making it possible to utilize the maximum water storage capacity. This means you can store more water and have a greater supply available when you need it the most.
  • Submersible pumps, on the other hand, take up space inside the tank, which can result in a slightly reduced water storage capacity. Depending on the pump size, this can result in up to 50 liters less water storage capacity.
  • By choosing an external pump, you can maximize your tank’s water storage capacity and ensure that you have a sufficient water supply for your needs. This is especially important in areas where water is scarce or in times of drought, where every drop counts.

Priming Requirement:

If you want to ensure that your pump is ready to supply water, you’ll need to prime it before operating. This is particularly important for external pumps, as they are not submerged and cannot naturally draw in water like submersible pumps.

Priming involves filling the pump with water to create a vacuum that will allow the pump to draw in water and start pumping.

To prime an external pump, you’ll need to locate the pump’s priming port and fill it with water until the water level reaches the top of the port. Then, turn on the pump and let it run for a few minutes to ensure that all air has been purged from the system.


Submersible pumps tend to be more expensive due to their construction, which includes a waterproof casing to protect the pump when submerged inside the tank. However, it’s important to remember that the initial investment may end up being worth it in terms of durability and efficiency over time.

Conversely, external pumps may be less expensive initially, but they may require additional equipment, such as a strainer basket or a priming pot. This can add to the overall cost of the pump, especially if it needs to be replaced frequently due to wear and tear.

When would you use a submersible pump?

When water needs to be extracted from a flooded area, a submersible pump is the best option due to its ability to fully immerse in water and extract it efficiently, like a fish swimming through water.

Submersible pumps are commonly used in situations that involve flooding, such as rising groundwater in cellars or basements, flooded boats, or flooded areas. These pumps are designed to be fully submerged underwater, allowing them to extract water from the source without any risk of damage from exposure to air.

The design of submersible pumps makes them ideal for use in deep wells or other sources of water that are difficult to access with external pumps. They are also more energy-efficient than external pumps, as they do not require as much power to overcome the resistance of the water.

What is the efficiency of an external pump?

You may not realize that external pumps typically have an efficiency rate of around 85%, making them a powerful tool for moving large volumes of water. However, it is important to note that many external pumps use journal bearings to support the rotating shafts.

These bearings require a minimum speed to function properly, which varies depending on the pump’s pressure. If the minimum speed is not met, the bearings can wear down quickly, causing damage to the pump and reducing its overall efficiency.

Can you run a submersible pump 24/7?

If you need to keep water circulating 24/7, consider the potential drawbacks, such as increased energy consumption and wear and tear on the pump’s components.

For example, imagine you own a small fish pond and want to keep the water clean and oxygenated for your fish. Running a submersible pump constantly may seem like a good idea, but it could lead to higher electricity bills and premature pump failure.

Submersible pumps are designed to fully submerge in water and are more commonly used in smaller ponds or water features. While they can technically run 24/7, it’s not recommended as it can lead to excessive wear and tear on the pump’s motor and impeller.

When would you use a submersible pump?

When would you use a submersible pump

Imagine having a small pond in your backyard that needs constant aeration and water circulation to keep your fish healthy and alive. This is when you would use a submersible pump for pond management.

A submersible pump is designed to be fully submerged in water, which makes it perfect for pond applications. It is also great for pumping water from wells, sumps, and similar sources. Submersible pumps are quieter, more efficient, and require less maintenance than external pumps.

To give you a better idea of the differences between a submersible pump and an external pump, here is a table that compares the two:

Submersible PumpExternal Pump
Designed to be fully submerged in waterDesigned to be located outside of water
Quieter, more efficient, and requires less maintenanceLouder, less efficient, and requires more maintenance
Ideal for pond applications, wells, sumps, and other similar water sourcesIdeal for transferring water from storage (cisterns) to use

Are submersible water pumps better than an external pump?

Now that you know when to use a submersible pump, let’s discuss whether it’s better than an external pump. The answer is yes, and for several reasons.

Firstly, submersible pumps don’t lose their prime because they are always submerged in water. This means that they are more reliable and require less maintenance compared to external pumps that can suffer from mechanical problems due to losing their prime.

Additionally, submersible pumps are more efficient and effective in pumping water from a well or a water source. Since they are closer to the water source, they don’t have to work as hard as external pumps to pull water up, resulting in less energy consumption and lower electricity bills.

Furthermore, they are generally quieter and have a longer lifespan since they are not exposed to the elements such as heat, cold, and dust.

Submersible vs External Water Pump: Choose the Right Pump According to Your Needs

Submersible pumps are more energy-efficient and quieter, while external pumps are easier to maintain and do not occupy any space within the tank. Depending on your specific needs, one pump may better suit you.

Whether you choose a submersible pump or an external pump, consider factors such as energy efficiency, noise level and maintenance. Ultimately, the choice of the pump depends on your specific needs and preferences.

We hope this blog post has helped you understand the differences between submersible and external pumps. So, dive in and make a splash with your new knowledge of pumps.

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