Submersible pumps are a key component in modern water, wastewater, and stormwater infrastructure. Designed to operate completely submerged, they are commonly used in situations where gravity flow is not possible or where surface-mounted pumps would be inefficient or impractical.
Above: Stormwater Pump Station with a Single Submersible Pump
This guide explains what a submersible pump is, how it works, how pump sizing is determined, and where submersible stormwater and sewage pumps are typically used in engineered pump station systems.
A submersible pump is a pump designed to operate completely underwater. Unlike surface-mounted pumps that rely on suction to draw liquid upward, a submersible pump sits directly in the fluid being pumped and pumps it to the discharge point. The electric motor is sealed within a watertight housing, with power supplied through a waterproof cable and gland, allowing the unit to operate safely and efficiently while submerged.
In clean water, stormwater, and wastewater applications, submersible pumps are typically installed in pump stations, wet wells, sumps, and tanks where consistent and automated pumping is required.
A submersible water pump is used to transfer water from below ground level to a higher discharge point where gravity alone cannot be relied upon. These pumps are widely used across residential, commercial, municipal, and industrial applications.
They are commonly installed in stormwater pump stations and drainage systems, sewer and wastewater pump stations, effluent transfer systems, water and wastewater treatment processes, and for construction or mine site dewatering. In stormwater and effluent applications, our GPD drainage and GPV vortex-style submersible sump pumps are designed to handle variable flows and light debris. In sewer applications, our GPC cutter and GPG grinder submersible sewage pumps are engineered to manage unscreened wastewater containing soft solids, reducing the risk of blockages and maintaining reliable operation.
A submersible pump works by converting electrical energy into hydraulic pressure that forces liquid upward through the discharge pipework.
When the pump is powered on, the electric motor drives an impeller. As the impeller rotates, it accelerates the liquid outward using centrifugal force, pushing it into the discharge system. Being that the pump operates fully submerged, it does not need to overcome air or suction limitations. This reduces the risk of cavitation and improves efficiency, particularly in deeper pump stations, wet wells, or confined underground installations.
Modern submersible pumps use high-efficiency motor designs to deliver consistent performance while reducing energy consumption over the pump’s operating life.
Above: XFP Submersible Pump Cutaway
Selecting the correct submersible pump is based on system requirements rather than the physical size of the pump itself.
Pump sizing considers how much liquid needs to be moved, the vertical and horizontal distance it must be pumped, and the conditions the pump will operate under. Engineers assess the required flow rate, total dynamic head including vertical lift and pipe friction losses, the type of liquid being pumped, and the expected solids content. Operating factors such as duty cycle and start/stop frequency are also considered to ensure the pump can perform reliably without excessive wear.
In sewage applications, cutter and grinder pumps are often specified where wastewater is unscreened or where discharge pipe sizes are restricted. By reducing solid size, these pumps help prevent blockages and maintain consistent flow through downstream pipework.
Submersible pumps are ideal for transferring liquid from below-ground pits, tanks, or chambers where installing or servicing a dry-mounted pump is not practical.
Such applications are:
stormwater pumping systems
sewer and wastewater pump stations
wastewater treatment facilities
industrial dewatering systems
wash-down systems
basement or pit drainage applications
Their compact design simplifies pump station layouts, eliminates the need for complex dry-well infrastructure, and enables reliable operation in confined or access-limited municipal and industrial environments.
Submersible pumps are valued for their reliability, efficiency, and compact installation footprint. Operating underwater eliminates many of the priming and suction issues associated with dry-mounted pumps, resulting in stable performance across a wide range of operating conditions.
When correctly specified, submersible water pumps offer long service life, reduced maintenance requirements, and quiet operation compared to above-ground pumping systems. Their ability to perform consistently in fluctuating water levels makes them a dependable choice for long-term infrastructure applications.
By supplying and integrating proven pumping technologies across stormwater, sewage, and water treatment systems, Global Water supports fit-for-purpose solutions designed for reliable, long-term performance.
Contact the Global Water team who will assist you with the sizing of a suitable submersible pump for your next project.
What is the difference between a submersible stormwater pump and a sewage pump?
Submersible stormwater pumps are designed for clean or lightly contaminated water, while submersible sewage pumps are built to handle solids and fibrous materials found in wastewater without clogging.
Can submersible pumps handle unscreened wastewater?
Yes. Sewage pumps and grinder-style pumps are designed to manage unscreened wastewater by reducing solid size and minimising the risk of blockages in pipework and valves.
Are grinder pumps required for all sewer applications?
No. Grinder pumps are typically used where small discharge pipe diameters or site constraints make the handling of larger solids difficult.
Do submersible pumps require priming?
No. Because submersible pumps operate fully submerged, they do not require priming and are less susceptible to air-related performance issues.
What maintenance do submersible pumps require?
Routine inspection is recommended. Pumps should be periodically removed from the sump or chamber for visual inspection, wear assessment, and electrical testing of the motor and cables.
Are submersible pumps safe?
Yes, when installed correctly. As with all electrical equipment, circuits should be protected by an earth leakage circuit breaker to ensure safe operation.
How are submersible pumps controlled?
Submersible pumps are typically controlled by float switches or level sensing devices that respond to changes in liquid level within the tank or chamber. In single-phase applications, pumps may be supplied with an inbuilt float switch.