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Submersible well pump: comparison with manufacturers' curves
Updated 12 Oct 2026 · WaterTally
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4-inch well pumps are long and narrow: they fit into a drilled well and can sit very deep. You need one when the water is beyond the suction reach of surface pumps (about 7–9 m in the data sheets we have read) or when a tank pump will not fit into the well.
Three pumps, three ways of declaring the data
- DAB S4 3/9 M and Pedrollo 4SRm 1/10-S publish a performance table with the tolerances of the ISO 9906 standard. The Pedrollo is built for high heads and low flows: its table stops at 1,800 l/h at 31 m.
- VEVOR 4SDM4/6 has a manual shared by nine models with maximum flow and head (110 l/min; 44 m, measured in the laboratory at zero flow) and no curve [78]. The input power is only on the shop page, where a customer-service answer also gives 45 m [41]. The calculator shows it in the group with maximum values only.
What to look at
- The curve at the head you need: depth of the water plus height of the outlet, hose losses and pressure for the sprinklers.
- Shaft power and input power are not the same thing: the DAB and Pedrollo data sheets give shaft power, the VEVOR manual output power and the VEVOR shop page input power.
- Control box, cable and protection devices are part of the electrical installation: they must be chosen and installed by a professional.
See also the guide on the 10-metre well.
Result
Enter depth, height, hose length and diameter and pressure to see the estimates.
What to do now
| Pump | Curve | Estimated flow | Enough? | Note |
|---|
“Declared” curves: points published by the manufacturer. “Max values only”: the manufacturer gives only maximum flow and head, joined by a straight line: an indicative estimate, not a confirmation. Depth and height are measured from the ground: the lift is their sum, and for surface pumps the depth is compared with the maximum suction depth as if the pump stood at ground level. Assumptions: clean water at 20 °C; smooth hose (roughness 0.007 mm, a high value for PVC and PE); fittings, bends, filters, valves and the suction hose are not included, so real flow will be lower. For surface pumps the real suction depth is lower than declared with a long or narrow suction hose. No extrapolation beyond documented points. This is a hydraulic estimate, not a system design. How we calculate and what we do not know
| DAB S4 3/9 M (4OL single-phase motor 0.55 kW at the shaft, kit with 15 m cable) | Pedrollo 4SRm 1/10-S (single-phase, 0.37 kW at the shaft) | VEVOR 4SDM4/6 (370 W output, 6 impellers, external control box) | |
|---|---|---|---|
| Declared maximum flow | not documented | not documented | 6,600 l/h [78][41] |
| Declared maximum head | not documented | not documented | 44 m [78][41](laboratory test at zero flow) |
| Maximum immersion depth | 250 m [40] | 200 m [39] | not documented |
| Declared input power | not documented | not documented | 810 W [41] |
| Cable length | 15 m [40] | not documented | 20 m [78][41] |
| Outlet connection | 1" 1/4 [40] | 1¼" [39] | not documented |
| Where to find it (ad) | Ad · search for the model at: Amazon · ManoMano | Ad · search for the model at: Amazon · ManoMano | Ad · search for the model at: Amazon · ManoMano |
Sources
- Water - Dynamic (Absolute) and Kinematic Viscosity — The Engineering ToolBox, retrieved 11 Oct 2026
- Surface Roughness Coefficients — The Engineering ToolBox, retrieved 11 Oct 2026
- 4SR-S / 4SR - elettropompe sommerse da 4", 50 Hz — Pedrollo S.p.A., retrieved 11 Oct 2026
- S4 - elettropompe sommerse 4", scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
- VEVOR pompa sommersa per pozzo 370 W, 110 l/min, prevalenza 44 m — VEVOR, retrieved 11 Oct 2026
- Deep well pump 3SDM2/21, 3SDM4/16, 3.5SDM4/11, 4SDM4/6, 4SDM4/10, 3SDM4/13, 3SDM3/16, 4SDM2/12 - User manual — VEVOR, retrieved 12 Oct 2026