Drilling a water well is only the first step in obtaining a stable water source. To ensure long-term, efficient, and energy-saving water supply, choosing the right submersible pump is the key link that cannot be ignored. In practical well drilling operations, most problems such as insufficient water output, frequent submersible pump burnout, short service life, or high energy consumption are caused by mismatched pump models—either the pump head is insufficient, the flow rate does not meet the demand, or the pump size is incompatible with the well pipe.
This article will clearly elaborate on the core factors that need to be considered when selecting a submersible pump after well drilling, and take a practical engineering case as an example: a water well with a total drilling depth of 200 meters, an 8-inch borehole, and a 6-inch PVC filter pipe. It will guide you step by step to select the most suitable submersible pump, which is directly applicable to well drilling teams, water supply projects, and foreign trade promotion scenarios for submersible pumps and drilling equipment.
Before selecting a submersible pump for your drilled well, you must first clarify the basic parameters of the well and your actual water demand. The following five factors directly determine the applicability and stability of the submersible pump, and none of them can be omitted.
Total Well Depth
The total drilling depth is the basic basis for selecting the submersible pump type. It determines the maximum depth at which the submersible pump can be installed and indirectly affects the required pump head. For deep wells, a multistage deep well submersible pump must be selected to ensure that the pump can lift water from a deep position to the ground stably. For shallow wells, a conventional submersible pump can meet the demand.
Static Water Level and Dynamic Water Level
These two parameters directly determine the installation position of the submersible pump and avoid the risk of pump burnout due to dry running:
Static water level: The vertical distance from the ground surface to the water surface in the well when the submersible pump is not running.
Dynamic water level: The stable water level in the well after the submersible pump runs continuously for a period of time.
The core principle is: The submersible pump must always be completely submerged below the dynamic water level. If the submersible pump is exposed to the water surface during operation, it will cause dry running, which will quickly lead to overheating and burnout of the pump motor.
Pump Head–Lifting Height
Pump head refers to the maximum vertical height that the submersible pump can lift water from the water surface to the target position, which is the most critical parameter for selecting a submersible pump. If the pump head is insufficient, the water cannot be lifted to the required height, or the water output will be extremely small; if the pump head is too high, it will cause energy waste and increase the use cost of the submersible pump.
The simple calculation formula for the required total pump head is:
Required total head = Dynamic water level + Pipeline loss + Safety margin
Among them, pipeline loss refers to the energy loss caused by water flow in the pipeline, and the safety margin is reserved to avoid insufficient pump head due to changes in water level or pipeline aging, ensuring the stable operation of the submersible pump.
Flow Rate—Water Output
Flow rate refers to the volume of water that the submersible pump can deliver per unit time, which is determined according to the actual use scenario of the well. Different usage requirements correspond to different flow rates of the submersible pump, and choosing an appropriate flow rate can avoid waste of resources and damage to the submersible pump.
Well Diameter and Pump Outer Diameter
This is a basic premise to ensure that the submersible pump can be smoothly installed into the well. The outer diameter of the selected submersible pump must be smaller than the inner diameter of the well pipe—if the submersible pump is too large, it will get stuck in the well pipe, making it impossible to install or disassemble, and even damaging the well pipe and the submersible pump.
Taking a common deep well drilling engineering case as an example, we will demonstrate the entire submersible pump selection process step by step, so that you can directly refer to it in actual well drilling operations.
Basic Parameters of the Well
Total drilling depth: 200 meters
Drilling diameter: 8 inches
Well pipe: 6-inch PVC filter pipe
Typical water level parameters:
Static water level: 30–40 meters
Dynamic water level: 60–80 meters
Determine the Maximum Outer Diameter of the Submersible Pump
The well uses a 6-inch PVC filter pipe, and its inner diameter is about 140–150 mm. According to the principle that “the submersible pump outer diameter must be smaller than the well pipe inner diameter”, the outer diameter of the selected submersible pump must be ≤ 140 mm.
Combined with industry specifications for well drilling and submersible pumps, the most suitable pump models are: 4-inch or small 5-inch submersible pumps. It should be emphasized that 6-inch submersible pumps cannot be selected, because their outer diameter exceeds the inner diameter of the 6-inch PVC pipe, which will cause the submersible pump to get stuck and cannot be installed in the well.
Calculate the Required Pump Head for the Submersible Pump
Taking the maximum dynamic water level (80 meters) as the calculation basis (to ensure that the submersible pump can work stably under extreme well conditions), the specific calculation is as follows:
Dynamic water level: 80 meters
Pipeline loss: 10–20 meters (calculated according to 15 meters for safety)
Safety margin: 20 meters
Total required head = 80 + 15 + 20 = 115 meters. To ensure the stable operation of the submersible pump, it is recommended to select a submersible pump with a head of ≥ 120 meters.
The most reliable choice in practical well drilling applications is: multistage deep well submersible pump with a head of 130–150 meters. This head range can not only meet the actual water lifting demand of the 200-meter deep well but also reserve sufficient space for changes in water level and pipeline aging, extending the service life of the submersible pump.
Select the Appropriate Flow Rate for the Submersible Pump
For a 200-meter deep well with a 6-inch PVC filter pipe, the water output is relatively stable. According to different use scenarios of the well, the recommended flow rates for the submersible pump are as follows:
Domestic use: 3–5 m³/h
Mixed use: 5–8 m³/h
Large-scale use: 8–12 m³/h
From the perspective of stability, durability, and energy saving of the submersible pump, the most universal and practical flow rate range is 5–10 m³/h. This flow rate can not only meet most daily and production needs but also avoid excessive load on the submersible pump, extending its service life and reducing energy consumption.
Match the Motor Power of the Submersible Pump
The motor power of the submersible pump needs to be matched with the flow rate and head. If the power is too small, it will cause the submersible pump to fail to reach the required head and flow rate; if the power is too large, it will cause energy waste and increase the use cost of the submersible pump.
For a submersible pump with a flow rate of 5–10 m³/h and a head of 130–150 meters, the suitable motor power range is 2.2 kW – 4 kW. Among them, the 3 kW three-phase submersible pump is the best all-round choice—it can not only meet the water supply demand of the 200-meter deep well but also has the advantages of energy saving, durability, and low failure rate, which is the most commonly used configuration in deep well drilling projects.
For a water well with a total drilling depth of 200 meters, an 8-inch borehole, and a 6-inch PVC filter pipe, the most suitable submersible pump configuration is as follows:
Pump type: 4-inch multistage deep well submersible pump
Flow rate: 5–10 m³/h
Head: 130–150 meters
Motor power: 3 kW
Voltage: 380V three-phase (suitable for industrial and rural power grids)
Pump outer diameter: ≤ 140 mm
Installation Notes for Submersible Pump
The installation depth of the submersible pump is recommended to be 90–100 meters. This depth can ensure that the submersible pump is always submerged below the dynamic water level even when the water level drops, avoiding dry running and pump burnout. At the same time, it is necessary to ensure that the submersible pump is installed vertically to avoid friction between the pump body and the well pipe during operation, which may damage the submersible pump and the well pipe.
To select a suitable submersible pump after well drilling, you only need to remember the following core principles, which can avoid 90% of the submersible pump selection errors in well drilling operations:
Determine the submersible pump diameter according to the inner diameter of the well pipe to ensure smooth installation;
Calculate the required pump head based on the dynamic water level, and reserve a sufficient safety margin to ensure stable operation of the submersible pump;
Select the flow rate of the submersible pump according to the actual use scenario to avoid excessive or insufficient water output;
Match the motor power of the submersible pump reasonably to achieve energy saving and durability;
Ensure that the submersible pump is always installed below the dynamic water level to avoid dry running and pump burnout;
Use multistage deep well submersible pumps for deep wells to ensure stable water lifting.
By following the above steps and principles, you can select a submersible pump that is fully matched with the drilled well, ensuring stable water supply, long service life, and low energy consumption. This selection method is suitable for both domestic and industrial well applications, and the article can also be directly used as foreign trade promotion materials for submersible pumps and well drilling equipment.
