Sewage Pump vs Sump Pump — What’s the Difference & Which One Do You Need?

Introduction

When purchasing water pumps, many users struggle to accurately distinguish between sewage pumps and submersible pumps, leading to incorrect selection, poor performance, and even frequent malfunctions. We’ll help you analyze the core differences between sewage pumps and submersible pumps. Understanding these differences is a crucial step in selecting the right pump and improving system reliability.

Basic understanding of the Sump pump and Sewage pump.

What Is a Sump Pump

A sump pump is a type of pump installed in the sump or low-lying areas. Mainly used to discharge clean water to prevent low-lying areas, such as basements and building sump pits, from accumulating water and flooding.

Mainly transports clean water, rainwater, and seepage water.

Common sump pumps include Submersible sump pumps, Vertical sump pumps， and Cast iron/Plastic casing sump pumps. The submersible sump pump is the most common and most widely used type.

What Is a Sewage Pump?

A sewage pump is a pump specially designed for transporting wastewater. Widely be used in building sewage, municipal engineering, and industrial wastewater systems. 

Whether the wastewater includes solids, solid particles, fibers, and feces， the sewage pump can treat it well.

There are several types of sewage pumps, among which the more common ones are

Flow channel sewage pumps， Vortex sewage pumps， Cutting-type sewage pumps, and submersible sewage pumps

Core Differences Between Sewage Pump and Sump Pump

Between the sewage pump and the sump pump, the core and the most significant difference is the media they can handle. This is also why we need to distinguish between these two types of water pumps.

Sump pump

Sump pumps can treat clean water, such as groundwater, seepage, cooling water, and non-corrosive industrial clean water. It can also handle rainwater from rooftops, ground runoff, and drainage ditches. Sump pumps can also handle water containing only a small amount of silt or tiny particles of 10-15mm.

Sewage pump

Wastewater pumps have a strong throughput capacity and can handle larger solid particles, commonly those with a diameter of 25mm-50mm or more. These pumps can handle them without any problems.

Sewage pumps can handle domestic sewage containing solid particles,  sewage with high impurities, and high fiber content. Even sewage containing long fibers and soft impurities can be easily handled by the sewage cutting pumps 

Other main differences

Aside from the most fundamental differences, sump pumps and sewage pumps differ in various aspects, from the pumps themselves to their intended use.

1. The structure and design 

Impeller

Sump pump: Semi-open or closed impeller

Sewage pump: Flow channel type (single/double flow channel)/Vortex type/Cutting type (with blade)

In comparison, the impeller design of a sewage pump is much better at preventing clogging and tangling than that of a sump pump, thus enabling it to better handle water containing impurities.

Overcurrent channel

Sump pump: The flow channels are relatively compact,t and the structure is simple.

Sewage pump: The wide flow channel with few bends and internal structure reduces impurity retention.

Anti-clogging function

Sump pump: Relying on filters to prevent impurities from entering

Sewage pump: Sewage pump can be equipped with a cutting disc/cutting ring to handle impurities, and features anti-winding designs such as anti-winding impellers and special inlets.

Internal protection

Sump pump： Sump pumps use a single mechanical seal or a simplified seal. The protection level is relatively low.

Sewage pump： Sewage pumps typically employ double mechanical seals or multiple seals, and also include an oil chamber to prevent sewage from entering the pump. The protection level will be higher, typically reaching IP68.

Material 

Sump pump: The sump pump is made of engineering plastics, stainless steel, and lightweight cast iron; more lightweight materials are used.

Sewage pump: Sewage pumps are typically made of cast iron or stainless steel, and their mechanical seals are wear-resistant and corrosion-resistant， and can operate in sewage.

Discharge Size

Sump pump： The discharge size is usually designed 1¼” or 1½.”It has high requirements for water quality and is easily clogged by impurities.

Sewage pump： Sewage pump’s discharge will be larger. Common models can pass through 25-50mm, while larger models can even pass through 80-100mm.

2. Installation 

Sump pump: Typically installed in semi-open or open spaces such as basement sump pits, the sump pump can be directly placed into the pit for use, making installation simple and convenient.

Sewage pump: They are typically installed inside sealed sewage wells or lift shafts, and are constantly submerged in sewage.

The most common installation method is automatic coupling guide rail mounting, where the sewage pump is lowered along the guide rail and automatically docks with the base. Fixed flange mounting is also available.

3. Service life and continuous working capacity

Sump pump: Sump pumps are designed for intermittent operation and are not suitable for long-term continuous operation. Relying on natural cooling requires a buffer period. Commonly, their service life is  5-10 years.

Sewage pump: Sewage pumps can operate continuously or for extended periods; some industrial-grade pumps can operate continuously for 24 hours. They are more resistant to high temperatures through liquid or oil cooling, and their overload protection systems are more comprehensive. With durable materials and protective function, the sewage pump can last for 8-15 years.

4. Energy Consumption

Sump pump: Typically used for pumping clean water or water with slight impurities. They experience low fluid resistance and low motor load during operation. Commonly used for clean water applications, the pump has a simple structure and generally offers high pumping efficiency.

Sewage pump: Due to the presence of solid particles in the transported medium, its impeller design is more complex. They maintain stable efficiency even under heavy loads, high flow rates, and high head conditions. Thus, they require more energy to overcome resistance and handle solid particles.

Comparison of typical application scenarios

The significant differences between sump pumps and sewage pumps can be seen from their respective application scenarios. They all used to treat water, but the application scenarios involved are completely different.

Sump pump:

• After rain, low-lying areas are prone to water accumulation and need drainage.
• Damp crawling spaces: Basements are typically built underground, making them more prone to dampness 
• Flood-prone areas: During the rainy season, flood-prone areas are prone to flooding.
• Foundation water leakage problems: Some houses have foundation water leakage problems, which can be easily solved by using sump pits.

Sewage pump:

• Basement sewage lifting, toilet, and kitchen wastewater discharge
• Sewage that cannot drain naturally from below ground level
• Sewage is discharged from residential and commercial buildings, such as hotels and apartments.
• Sewage treatment plant/industrial wastewater discharge
• Clogging-prone conditions, such as those containing long fibers, plastic bags, and rags.
• Transportation of livestock and poultry manure and discharge of livestock wastewater from agricultural and breeding farms.

The impact of using the wrong water pump

Using a sump pump in sewage or using a sewage pump to pump water from a sump will cause problems. Understanding the problems will help you make a more careful choice when selecting a water pump.

Use a sump pump to pump sewage.

• The inlet and impeller are blocked by solids and fibers, causing a significantly low flow rate or even a complete stop.
• Motor overload, triggering the thermal protector, or even causing the pump to burn out.
• Impurities wear down the seals, damaging the mechanical seal and allowing wastewater to enter the motor, damaging the pump.
• The float ball is blocked, causing frequent pump start-stop cycles, damaging internal components, and significantly reducing the pump’s lifespan.

Use a sewage pump to pump the accumulated water

• Sewage pumps are typically made of cast iron, and their manufacturing process is more complex and therefore more expensive.
• Even treating a small portion of the water, the energy consumption of sewage pumps is very high.
• Noise is also a factor to consider; sewage pumps are generally noisy, and if installed in a basement, the noise will be noticeable.
• Sewage pumps are usually quite large, requiring more space. If they have flexible functions such as cutting or grinding, the pump will be even heavier and more difficult to move.

How to Choose the Right Pump — A Basic and Quick Selection Guide

From the selection guide, you can find out the difference between a sump pump and a sewage pump. It’s more Intuitive and easier to refer to. It helps you quickly and easily choose between a sump pump and a sewage pump, saving you a lot of time and effort.

Conclusion

The essential difference between sump pumps and sewage pumps lies in the different media they handle. If the media contains solids, fibers, or feces, a sewage pump with higher anti-clogging capabilities is needed; if it is only clean water, rainwater, or seepage, a sump pump is more advantageous in terms of efficiency and cost. Only by selecting the correct model according to the actual working conditions can the long-term stable operation of the system be guaranteed, avoiding unnecessary failures and cost waste.

FAQ

Q1:Is a sewage pump the same as a cutter pump?

A1:A cutting pump is just one type of sewage pump, and the two are not entirely equivalent. A sewage pump is a general term for water pumps used to transport sewage containing impurities, solid particles, or fibers. A cutting pump specifically refers to a sewage pump equipped with a cutting device, such as a blade or cutting ring at the pump inlet or impeller front end.

Q2:Can sump pumps run dry?

A2: When the pump starts without water entering the pump body, or when the water level is too low during operation (such as in a sewage tank where the water level is too low or the inlet is blocked), the sewage pump will run dry. Dry running can lead to mechanical seal burnout, water leakage, and motor overheating or even burnout. During use, dry running should be avoided as much as possible.

Q3:What  sewage pump do I need?

A3:First, determine the impurities in the wastewater. If it contains long fibers or debris, a cutting-type wastewater pump is needed. If the liquid mainly contains particles or silt, a large-channel or dual-channel wastewater pump is more suitable. If the wastewater contains only a small amount of impurities, a regular wastewater pump is sufficient. Next, select the appropriate model based on the head, flow rate, and installation method.

Q4:Can a sump pump be used continuously?

A4: Sump pumps can operate continuously for short periods, but are not suitable for long-term continuous operation. Most sump pumps rely on water cooling, and prolonged operation can easily lead to motor overheating. Furthermore, their structure and components are better suited for start-stop operation; continuous operation will accelerate wear and shorten the pump’s lifespan.

Q5:Why is my sewage pump making noise?

A5:Perhaps hard objects such as stones, metal, and plastic enter the impeller in the sewage. The inlet channel/the impeller may be clogged, or bearing wear, lack of lubrication, or damage. The water pump is not securely fixed, and the base is uneven or lacks shock absorption. If the noise is very loud， please disassemble the pump and check.