Jet Pump — How It Works, Types, and Troubleshooting

A jet pump is a surface-mounted water pump that uses a high-pressure water jet to create a vacuum and draw water from a well or other water source into the supply system.

Jet Pump diagram — labeled parts, dimensions, and installation context

What It Is

Jet pumps work by forcing a portion of the pressurized output water through a narrow nozzle called a jet or ejector, which creates a low-pressure zone that draws in water from the well. The combined flow is then delivered to a pressure tank. Because the mechanical components — motor, impeller, and ejector — are located above ground at the pressure tank, jet pumps are easier to service than submersible pumps.

Jet pumps rely on atmospheric pressure and hydraulic principles rather than being submerged near the water source. This limits how deep they can lift water effectively.

Types

Shallow-well jet pumps have the ejector built into the pump body and can lift water from depths up to about 25 feet. Deep-well jet pumps have a separate ejector assembly installed in the well casing, connected to the pump via two pipes, and can draw water from depths up to 80–120 feet depending on the model.

Where It Is Used

Jet pumps are used in residential and light commercial properties served by private wells. They are common in rural areas without access to municipal water systems. Shallow-well versions are also used for irrigation systems, pond circulation, and water transfer applications.

How to Identify One

A jet pump is a motor-driven unit typically installed near a pressure tank in a basement, utility room, or pump house. Look for a cast-iron or stainless housing with inlet and outlet ports and a pressure switch attached to the outlet pipe. A deep-well installation will have two pipes running down into the well casing.

Replacement

Jet pumps are replaced when the motor fails, the impeller wears, or the pump loses prime and cannot recover. Matching the horsepower rating, well depth, and flow rate (GPM) of the existing pump is essential when selecting a replacement.

Jet Pump — FAQ

What is the difference between a jet pump and a submersible pump?

A jet pump is installed above ground near the pressure tank and uses a hydraulic ejector to draw water up from the well. A submersible pump is installed inside the well casing below the water level and pushes water up under pressure. Submersibles are more efficient at greater depths, while jet pumps are easier to service because all components are accessible at the surface.

Why does a jet pump lose prime?

Loss of prime usually means air has entered the suction line. Common causes include a cracked inlet pipe, a worn foot valve or check valve that allows water to drain back when the pump is off, a drop in the water table below the pump's lift capacity, or an air leak at a pipe joint. Repriming involves filling the pump housing with water and restarting.

How deep can a jet pump pull water from?

A shallow-well jet pump can typically lift water from depths up to 25 feet. A deep-well jet pump with a submersed ejector assembly can reach depths of 80–120 feet, though efficiency drops at greater depth. For depths beyond 120 feet, a submersible pump is the standard solution.

How long does a jet pump last?

A well-maintained jet pump typically lasts 10–15 years. Motor bearings and impellers are the most common wear items. Running the pump dry, frequent short-cycling due to a waterlogged pressure tank, and sediment in the water supply all shorten pump life.

What causes a jet pump to short-cycle?

Short-cycling — the pump turning on and off rapidly — is almost always caused by a waterlogged pressure tank where the internal air bladder or air charge has failed. The tank needs to be recharged with air or the bladder replaced. Running a pump in short-cycle condition accelerates motor and pressure switch wear.