In most cases, the issue is not the pump itself — it is incorrect pump selection.
Some users only focus on motor power without calculating the required head. Others choose low-cost pumps while ignoring water quality and corrosion risks. Some select oversized pumps, resulting in unnecessary energy consumption and operating costs.
In reality, once you understand several key factors — flow rate, head, well conditions, water quality, and power requirements — choosing the right agricultural irrigation submersible well pump becomes much easier.
This guide will help you calculate and select the right pump step by step.
1. Calculate Flow Rate First: How Much Water Do You Need?
Flow rate (Q) determines how much water the pump can deliver per hour.
Formula
Flow Rate (m³/h)=Irrigation Area×Water Demand per Acre
Traditional flood irrigation usually requires around 5m³ of water per acre per hour. Drip irrigation systems require less flow, while sprinkler irrigation often requires higher flow rates.
2. Calculate Total Head: How Much Lifting Power Does the Pump Need?
Many users only consider well depth while ignoring pipeline losses.
Correct Formula
Total Head
=Net Head+Pipeline Loss+Safety MarginH_t = H_n + H_p + H_s
Practical Example
Suppose:
- Dynamic water level: 60m
- Horizontal pipeline length: 80m
- Two pipe elbows
Calculation:
- Net head = 60m
- Pipeline loss ≈ 8m
- Elbow loss ≈ 2m
Basic total head:
60 + 8 + 2 = 7060+8+2=70
After adding 15% safety margin:
70 \times 1.15 \approx 8070×1.15≈80
Conclusion: A submersible well pump with at least 80m head is recommended.
⚠ Important:
Do not select a pump based only on well depth. Dynamic water level is the key factor.
3. Well Diameter and Installation Depth Matter
Not every pump is suitable for every well.
Common Well Diameter Reference
| Well Diameter (mm) | Recommended Pump Series | Typical Applications |
|---|---|---|
| 175mm | 175QJ Series | Small farmland irrigation, household water supply |
| 200mm | 200QJ Series | Agricultural irrigation, deep well water supply |
| 250mm | 250QJ Series | Medium and large farms, municipal water supply |
| 300mm | 300QJ Series | High-flow irrigation, industrial water supply |
| 350mm | 350QJ Series | Large irrigation systems, mining drainage |
| 400mm | 400QJ Series | Industrial water transfer, high-capacity pumping |
| 450mm | 450QJ Series | Water plants, centralized agricultural water supply |
| 500mm | 500QJ Series | Ultra large flow water supply projects |
| 550mm | 550QJ Series | Large industrial and municipal projects |
| 600mm | 600QJ Series | Ultra high-flow deep well and water transfer projects |
The pump outer diameter should be at least 20–25mm smaller than the well inner diameter to ensure smooth installation and stable performance.
The pump should also be installed 3–5 meters below the dynamic water level and at least 1 meter above the bottom of the well to avoid sand intake.
4. Water Quality Determines Pump Lifespan
Different water conditions require different pump materials.
| Water Condition | Recommended Material |
|---|---|
| Clean Fresh Water | Cast Iron / 304 Stainless Steel |
| Chloride or Coastal Water | 316L Stainless Steel |
| High Sand Content | Wear-Resistant Impeller |
| Acidic or Alkaline Water | 316L Stainless Steel |
Material Selection Tips
Cast Iron
Economical and suitable for clean freshwater irrigation projects with limited budgets.
304 Stainless Steel
Excellent cost-performance balance with good corrosion resistance for most agricultural irrigation systems.
316L Stainless Steel
Recommended for coastal regions, saline water, corrosive environments, and long-term reliability.
If you are unsure about water corrosiveness, it is recommended to perform a water quality test before selecting the pump material.
5. How to Calculate Pump Power?
Power (kW) = Flow Rate (m³/h) × Head (m) × 0.00272 ÷ Pump Efficiency
Pump efficiency typically ranges between 60% and 80%; generally, 70% is used for a conservative estimate.