Glossary of Water Pump Terms

Whether you're looking for a new water pump for your house, business, or farm, understanding water pump terminology is key to making informed decisions. This glossary is designed to explain technical terms and pump-related components in clear, accessible language, helping you navigate specifications, system design, and product features with confidence.

In this glossary, you'll learn:

• Key definitions for pump types, components, and performance metrics
• How different technologies like submersible, jet, and booster pumps work
• Important concepts such as head pressure, priming, GPM, and PSI
• Control systems, safety features, and efficiency terms used in the industry

Explore the most common terms from A to Z and build your knowledge as you plan, purchase, or maintain your pumping system.

Air Lock 

A condition that occurs in fluid handling systems where trapped air prevents the normal flow of liquid. It typically occurs in sections of pipeline where air becomes trapped at high points, creating a blockage due to the compressible nature of air compared to water. In water pumps, especially centrifugal and jet types, air locks can prevent successful priming of the system, leading to pump suction failure. 

Automatic Pump 

A fluid transfer device equipped with integrated sensors or control mechanisms that allow it to start and stop operation without manual intervention. These pumps operate in response to predefined parameters. 

Automatic activation is commonly achieved using float switches, pressure switches, electronic controllers, or Variable Frequency Drives (VFDs). A common example is a sump pump with a float switch that activates the pump motor when the water level rises above a certain height.

Bailer 

A cylindrical device used to retrieve water samples, remove debris, or manually extract water from wells, boreholes, or other confined water sources. 

Typically constructed from stainless steel, PVC, or polyethylene, a bailer operates through gravity and hydrostatic pressure without the need for external power. It features a bottom check valve that allows water to enter but prevents it from escaping when the device is lifted.

Booster Pump 

A mechanical device designed to increase water pressure in a water distribution system. Surface booster pumps are typically used in applications where the existing water pressure is insufficient for functional requirements, such as in tall buildings, irrigation systems, municipal supply networks, or residential plumbing fed by low-pressure sources like wells or storage tanks.

Check Valve 

Also known as a non-return valve or one-way valve, a check valve is a mechanical device that permits the flow of water in one direction only and prevents backflow in piping systems. 

It operates automatically and does not require manual intervention or external control mechanisms. Check valves are critical in preventing reverse flow that could damage equipment, contaminate water sources, or disrupt system functionality.

Control Box 

An enclosure that houses electrical components used to manage, monitor, and operate electric motor-driven systems, such as water pumps. A pump control box regulates the startup and operation of the motor, and protects the motor by integrating control elements such as capacitors, relays, contactors, overload protection, and sometimes electronic logic or variable frequency drive (VFD) interfaces.

Deep Well 

A type of water well that extends more than 25 feet below the ground surface, typically reaching depths of hundreds of feet to access confined or unconfined aquifers. 

Deep wells are usually constructed using drilled methods and lined with casing and well screens to maintain structural integrity and control groundwater inflow. Deep wells are less susceptible to surface contamination due to the natural filtration that occurs through thicker geologic layers.

Diaphragm Pump 

A diaphragm pump is a positive displacement pump that uses a flexible diaphragm and check valves to move water. The pumping action is achieved by the back-and-forth movement of the diaphragm, which creates alterations in pressure within the pump chamber, drawing in and expelling liquid in a controlled and sealed process. 

Discharge Head 

A discharge head is a component of total dynamic head (TDH) and refers specifically to the pressure or energy required to move water vertically from the pump’s centerline to the final point of discharge. Discharge head can include static discharge height as well as any pressure that must be maintained at the outlet point, such as in pressurized tanks or distribution networks.

Dry Run Protection 

A preventive control feature in pump systems that automatically shuts down a pump or prevents it from operating when no water is present at the pump inlet. This functionality is critical in protecting pumping equipment from damage due to overheating, cavitation, or mechanical wear that can occur when operating under low- or no-flow conditions. 

Electric Motor 

An electromechanical device that converts electrical energy into mechanical energy through electromagnetic interactions. In pump systems, electric motors serve as the prime mover, rotating a shaft that transmits torque to drive components such as impellers or pistons, enabling water movement through a system. 

End Suction Pump 

A type of centrifugal pump characterized by a single inlet (suction opening) on one end, and a discharge outlet located on the top of the pump casing. It is one of the most commonly used pump configurations in water, HVAC, and industrial systems due to its simplicity, compact design, and cost-effectiveness.

Foot Valve 

A foot valve is a type of check valve installed at the intake (suction) end of a pump suction line, typically at the bottom of a well, tank, or water source. Its primary function is to maintain prime in the pump by preventing air locks from the reverse flow of liquid when the pump is turned off. 

Foot valves are designed to permit unidirectional flow, allowing water to enter the suction line while stopping it from flowing back out, thereby keeping the suction line filled with liquid and eliminating the need for frequent re-priming of the pump.

Friction Loss 

The reduction in pressure or head that occurs in a water system due to the resistance created by the contact between the moving water and the internal surface of the piping, fittings, valves, or other hydraulic components. 

Friction loss is a critical factor in the design and operation of pumping systems, irrigation networks, and plumbing layouts, as excessive friction loss can result in decreased energy efficiency, lower flow rates, and increased pumping costs.

Gallons Per Minute (GPM) 

A unit of volumetric flow rate used primarily in the United States to measure the quantity of liquid moving through a system in one minute. 

It is commonly abbreviated as GPM and is equivalent to 3.785 liters per minute (L/min). In a water transport and pump system design, GPM is a critical performance parameter that defines the flow capacity of equipment such as pumps, valves, nozzles, and piping systems.

Grinder Pump 

A type of wastewater conveyance system that combines a macerating mechanism with a submersible pump to reduce solid waste into a fine slurry and transport it through small-diameter pressurized sewer lines. 

Head Pressure 

A measure of the height of a water column that a pump must overcome to move liquid from one point to another. In pumping systems, it is typically expressed in units of feet (ft) or meters (m) of fluid and is used to quantify the energy required to lift or move water to a certain elevation. 

Horizontal Pump 

A centrifugal or positive displacement pump configuration in which the pump shaft is oriented parallel to the ground. This layout positions the motor and pump on a shared base plate or frame, with the impeller housing located horizontally and inlet/outlet connections typically aligned for easy integration into horizontal piping systems. 

Impeller 

A rotating component of a centrifugal pump, typically composed of vanes or blades designed to transfer energy from a motor to the water being pumped. Its primary function is to increase the water’s velocity and pressure as it passes through the pump housing. The impeller spins at high speed, converting mechanical energy into kinetic energy, which is then mostly converted into pressure energy in the volute or diffuser section of the pump. While stainless steel impellers offer the best durability of any material, modern thermoplastic impellers also deliver great performance over the lifetime of a water pump.

Jet Pump 

A type of centrifugal pump that uses a Venturi-effect nozzle (jet assembly) to create suction and draw water from a source, typically a shallow or deep well. Jet pumps operate by combining mechanical pumping with fluid dynamics; a high-velocity jet of water creates low pressure at the suction point, inducing water flow from the well. 

Lift 

The vertical distance a pump must raise water from its source level (typically a water surface, reservoir, or well) to the pump inlet or outlet. It quantifies how far the water must be moved vertically against gravity and is a key factor in determining a pump’s ability to move liquid effectively under suction conditions. Vertical lift is a key component of designing effective water systems, especially for systems that require pumping to a multi-story building or elevated water tanks.

Magnetic Drive Pump 

A type of sealless centrifugal or positive displacement pump in which torque is transmitted from the motor to the pump shaft through a magnetic coupling rather than a traditional mechanical shaft seal. 

This design eliminates the need for dynamic seals, reducing the risk of water leakage and making mag-drive pumps ideal for handling hazardous, corrosive, or ultra-pure fluids in chemical processing, pharmaceuticals, electronics manufacturing, and specialty fluid systems.

Multi-Stage Pump 

A centrifugal pump design that utilizes two or more impellers operating in series within a single pump housing to increase water pressure progressively with each stage. Each impeller adds energy to the water, allowing the pump to achieve a higher total dynamic head (TDH) compared to single-stage pumps, while maintaining moderate flow rates. 

Pitless Adapter 

A specialized plumbing fitting used in well water systems to enable a sanitary, frost-proof connection between a submersible pump discharge pipe and the horizontal water service line leading to a structure. 

It is installed on the well casing, typically below the frost line, and facilitates a sealed, below-ground connection that eliminates the need for a traditional well pit or exposed above-ground piping.

Positive Displacement Pump

A type of pump that moves fluid by trapping a fixed volume in a cavity and mechanically displacing (pushing) it through the pump’s outlet. 

Unlike centrifugal pumps, which impart velocity to the water, positive displacement pumps deliver a constant flow regardless of discharge pressure, making them ideal for high-viscosity fluids, metering applications, and systems requiring precise flow control.

Pounds per Square Inch (PSI) 

A non-SI (non–International System of Units) unit of pressure commonly used in the United States and other countries for measuring the force exerted on an area of one square inch.

Power Rating 

The maximum continuous amount of mechanical or electrical power that a device can deliver or consume safely under specified operating conditions. 

Power rating is most commonly expressed in units of horsepower (HP) or kilowatts (kW), and it indicates the capacity of the motor to drive the pump at its designated performance level without overheating or mechanical failure.

Pressure Switch 

An electromechanical device used to monitor the pressure of a fluid (liquid or gas) in a system and activate or deactivate electrical circuits when the pressure reaches predefined setpoints. A pressure switch serves as a critical control element, protecting equipment, maintaining system stability, and automating water handling operations.

Pump Housing 

The external structural enclosure that contains and supports the internal components of a pump, such as the impeller, shaft, seals, and bearings. 

Pump Shaft 

A mechanical component that transmits rotational energy from a driver to the impeller or other pumping elements within a pump. 

It is typically a cylindrical metal rod that forms the central axis of rotation and is engineered to operate under both radial and axial loads. The shaft ensures torque transfer while maintaining precise alignment of rotating components to achieve efficient and stable fluid pumping.

Recirculation 

The intentional or unintentional return of a portion of the fluid from the discharge side of a system back to its source or suction inlet. 

It may be incorporated by design to maintain system stability, prevent overheating, ensure constant flow through equipment, or facilitate consistent fluid quality. 

Safety Relief Valve 

A pressure-relief device designed to protect equipment, piping systems, and pressure vessels from overpressure conditions by releasing excess internal pressure in a controlled manner. 

It is essential in fluid systems involving gases, steam, or liquids where uncontrolled pressure rise could result in equipment failure, explosion, or personnel hazard.

Self-Priming Pump 

A type of centrifugal pump specifically designed to evacuate air from the suction line and create vacuum conditions that draw fluid into the pump without the need for manual priming. 

It combines the air-handling capabilities of a positive displacement pump with the flow efficiency of a centrifugal pump. Self-priming pumps are widely used in applications where the pump is located above the fluid level, such as in wastewater lift stations, stormwater drainage, and industrial sump systems.

Solar Pump 

A water transfer system powered by electricity generated from solar photovoltaic (PV) panels. 

These pumps are commonly used for water supply in agriculture, livestock watering, rural communities, and other off-grid applications where access to conventional electric power is limited or unavailable. 

Submersible Pump 

A submersible pump is a type of pump designed to operate while completely submerged in the fluid it is intended to move. 

The hermetically sealed motor and pump assembly are housed within a watertight casing, allowing the unit to function efficiently under the surface of a liquid, typically in wells, sumps, tanks, or sewage systems. 

Below are submersible pump types, their key features and what they are best suited for:

Sump Pump 

An electrically powered pump designed to remove accumulated water from a sump basin or pit, typically located in the lowest part of a building such as a basement or crawlspace. 

Its primary function is to prevent flooding and structural water damage by automatically discharging groundwater or stormwater away from a building’s foundation to a designated drainage area, such as a storm sewer, dry well, or detention basin.

Torque Arrestor 

A mechanical device installed on the drop pipe above a submersible pump to absorb and control the reactive torque produced by the motor during startup and shutdown. 

This torque can cause the drop pipe to twist or rotate within the well casing, potentially leading to pipe damage, cable entanglement, or misalignment. It anchors the drop pipe centrally within the well casing and restricts rotational movement, enhancing the mechanical stability and longevity of the pump installation.

Total Dynamic Head (TDH) 

A key performance metric used in pump system design that represents the total equivalent height a pump must overcome to move water through a system. 

It is the sum of all energy losses and gains in the pumping system, typically measured in feet or meters of fluid column. TDH determines the amount of work a pump must perform and is critical in selecting and sizing pumps for applications such as water supply, wastewater, irrigation, and industrial fluid handling.

Variable Speed Pump

A variable speed pump is a pump that operates at adjustable rotational speeds to match system demand, offering precise control over flow rate and pressure. 

This modulation is typically achieved through a variable frequency drive (VFD), which adjusts the frequency and voltage supplied to the pump’s electric motor. 

By varying pump speed in real time based on system pressure, flow sensors, or user-defined settings, variable speed pumps optimize energy efficiency, prolong equipment life, and deliver stable performance in dynamic pumping environments.

Water Horsepower 

The theoretical power required to move water at a specific flow rate and head, assuming complete hydraulic efficiency and no mechanical or frictional losses. 

It quantifies the energy output needed to lift or transport water and serves as a baseline for sizing pumping equipment and evaluating actual pump or motor performance.

Below is a table comparing terms and units similar to water horsepower that are used for pumping and plumbing equipment;