Factors to keep in mind while choosing between oil filled and water filled pumps.

Submersible pumps come in various shapes and sizes; broadly classified based on the type of fluid being pumped, for example, clean-water pumps for pumping utility water; sewage pumps working with waste and so on. Submersible pumps can also be further classified based on the type of cooling technique deployed. In this article, we will discuss at length about water-filled and oil-filled submersible pumps, their features, advantages and disadvantages. We believe this article can help you make an informed decision while choosing between the two.

Oil-filled pimps VS Water filled pumps: Technical explained

As submersible pumps are submerged in the fluid being handled, the cooling of the electrical motor cannot be done by traditional air cooling. The motor, hence, is filled with cooling liquid to ensure that the motor remains sufficiently cool during operations.
In a water-filled submersible motors, water is the cooling liquid while it is oil in a oil-filled motor.
Electrically, the winding design changes as per the choice of coolant. A water-cooled motor is wound using insulated cable; generally PVC, to ensure hassle-free operation and easy maintenance. Oil itself being an electrical insulant, oil-filled motors are wound with enamel coated conductors. In general, oil-filled pumps require lesser operational maintenance and longer service life compared to water filled pumps. However, in case of insulation failures and short-circuits, restoring oil-filled motor is difficult and time consuming.


Oil filled vs Water filled pumps: Which one to choose

Several factors need to be considered while choosing between water-filled and oil-filled pumps namely:

Depth of Well:

Water-filled pumps work well when the pumping depth is less that 50 mtrs. It is advisable to go for an oil-filled pump for higher depths due to oil induced cushion pressure that allows better operation at higher depths.

Discharge Rate:

Discharge rate refers to the amount of water pumped per minute. If the discharge rate is higher it is better to go for a oil-filled pump, as they allow higher motor loading for operations. Discharge rates are directly proportional to the horsepower ratings of the motor.

End Utility & Application:

Overtime, due to wearing down of the seals, an oil-filled pump may spill oil into the well, deeming the water unsuitable for consumption. As a result, oil-filled pumps are found to be more suitable for handling waste water, flood and drainage pumps and as general water distribution pumps. Water-filled pumps are found to be more suitable for handling drinking water handling and distribution.

Maintenance Cost:

For high head, high flow applications, oil-filled pumps are the preferred choice due to their ability to ensure smooth and trouble-free operation. Conversely, in smaller-scale operations, water-filled pumps outperform oil-filled counterparts in terms of overall operability and maintenance ease. When it comes to repairs, water-filled pumps are notably simpler to service in case of winding failure.

However, it’s essential to consider long-term durability. Rusting is a common issue associated with water-filled pumps, leading to cogging and eventual failure. In contrast, oil-filled pumps exhibit resistance to oxidation, providing rust-free operation over extended periods. Additionally, oil-based lubrication enhances the longevity of internal mechanical components, contributing to the pump’s lifespan.

Energy Efficiency:

Oil-filled pumps are more energy efficient than water-filled pumps resulting in lesser power consumption/ litre of water pumped, thereby enabling better overall performance.

Highly efficient oil filled & Water filled pumps from LUBI Electronics

LUBI Electronics offers end-to-end submersible solar pumping systems in the range of 1-100 HP for various applications. The solar pumps are stainless steel built and come in water-filled and oil-filled variants.


The pump controllers of the solar pumping systems have been specially developed to handle low voltages and can be efficiently used in solar system comprising of >500Wp solar panel configuration.


LUBI solar pumping systems adhere to the latest MNRE guidelines and come with a promise of high efficiency and superior output.


About LUBI Electronics

LUBI Electronics is a leading company in India, exhibiting expertise in the automation, solar, and control panel industry.

Our solar offerings include best-in-class solar modules, solar pumps, solar pump controllers and solar inverters.

For more information on our offerings, please reach out to us at lubi@lubielectronics.com.

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