Submersible Groundwater Pumps: A Practical Guide for Residential Wells
Submersible groundwater pumps play a crucial role in supplying clean, reliable water to residential homes. Designed to operate below the waterline inside a well, these pumps push water to the surface using a submersible motor and a multistage centrifugal pump. If you’re replacing a pump, troubleshooting performance issues, or choosing equipment for a new well, understanding how these systems work is essential.
This guide covers what submersible pumps do, how to select the right one, major brands to consider, and the system components involved in a residential groundwater setup.
What Is a Submersible Groundwater Pump?
A submersible groundwater (GW) pump is a centrifugal pump attached to a sealed motor and lowered into a well. The pump pushes water upward from its intake to the surface. Residential water systems commonly use 115V or 230V single-phase, 60Hz motors.
Inside the pump, multiple impellers (stages) increase pressure, not flow. Flow rate depends on how much head pressure the pump must overcome. As pressure increases, flow decreases.
The pump and motor are separate components and can be replaced independently.
2-Wire vs. 3-Wire Motors
When identifying pump wiring, count the wires excluding the ground.
- 3-Wire + Ground motors require a control box, which houses relays and capacitors that assist in starting the motor and reduce inrush amperage.
- 2-Wire + Ground motors have the start components built into the motor.
Older installations may not include a ground wire.
Why Matching Pump Flow Rate Matters
When replacing a groundwater pump, always match the pump’s design flow rate or have your well professionally tested for recharge rate. The recharge rate indicates how quickly the aquifer refills the well.
Oversizing the pump can cause the well to be pumped dry and may damage the motor. You can switch manufacturers, but you must maintain equivalent flow characteristics.
Major Manufacturers
Two leading manufacturers in the U.S. residential groundwater market include:
Grundfos
Franklin Water Systems (Franklin Electric)
- Makes Tri-Seal pumps designed for wells with higher turbidity.
- Offers the 3200 Series, a narrow-diameter pump ideal for tight 4-inch wells.
How to Choose the Right Submersible Pump
Manufacturers publish pump curves showing the relationship between:
- Vertical axis: Head/pressure
- Horizontal axis: Flow rate
To size a pump correctly:
- Determine Total Dynamic Head (TDH):
- Standing water level below surface
- Vertical elevation difference between well head and home/tank
- Pressure switch shutoff pressure × 2.31 = feet of head
- Example: 60 PSI × 2.31 = 138.6 ft
- Find the intersection of your needed flow rate and calculated head on the pump curve.
- If your requirement falls between two pumps, choose the higher curve.
- Horsepower is the last consideration: choose based on the pump curve, not the other way around.
Other Key Components in a Residential Pumping System
Pressure Switch
Controls pump operation. Common settings:
- 30/50 PSI
- 40/60 PSI
The 20 PSI differential prevents rapid cycling. Pressure is adjustable.
Pressure Tank (Bladder/Expansion Tank)
Provides water storage and stabilizes pressure to reduce motor cycling, extending pump life.
Motor Lead
Carries power from the pressure switch or control box to the pump. Wire gauge depends on horsepower and distance.
Drop Pipe
Connects to the pump discharge and delivers water to the surface.
Pitless Adapter
Required in regions where pipes must run below the frost line. Allows water to exit the well casing underground, preventing freezing.
Disconnect Switch
May be required by code for quick electrical shutoff during service.
Final Thoughts
Selecting the right submersible groundwater pump is critical for the long-term performance and reliability of your residential water system. By understanding pump curves, motor wiring, total dynamic head, and supporting system components, you can make informed choices — whether you’re replacing a failing pump or designing a new setup.
Environmental Equipment & Supply offers a wide range of groundwater pumps, components, and accessories from leading manufacturers like Grundfos and Franklin Water Systems. Our team can help you select the right system based on your well depth, water needs, and local conditions.
Have questions or need help choosing a pump?
Contact Environmental Equipment & Supply our experts are ready to assist.