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Which garden irrigation pump: calculator for wells and tanks

Enter depth, height difference and hose: the calculator estimates how much water each irrigation pump gives in your system, using manufacturers' curves.

Updated 12 Oct 2026 · WaterTally

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Your system

The water
From ground level, the same reference as the outlet height. Above-ground tank or water at ground level: 0.

How do I measure it?

Lower a weighted string until it touches the water, with the pump off, and measure the distance from ground level. If you measure from the well rim, subtract the rim’s height above the ground: otherwise the depth comes out larger than it is. Repeat after drawing water for a while: the level drops while pumping, and the lowest one counts.

Where it has to go
The highest point to reach: sprinkler, tap, raised tank.

0 if the water flows out freely, for example into a tank.

Where do I find it?

For sprinklers and drippers it is in the datasheet, in the flow–pressure table of the nozzle you will use. For a plain garden tap you can enter 0.

The delivery hose

Where do I find it?

Use the inner diameter, not the outer one. Garden hoses sold as “1/2 inch” are usually about 13 mm inside and “3/4 inch” about 19 mm, but it varies: check the hose datasheet or measure it.

How much water you need
Sum of the flows of the sprinklers running together.

Work it out with a bucket and stopwatch

Result

Enter depth, height, hose length and diameter and pressure to see the estimates.

Curves “read from the manufacturer’s chart”: points read from a published chart, not a table, rounded to the precision of the reading. For these pumps the calculation uses the lowest and the highest curve the reading allows: the flow is a range, and “enough” or “not enough” holds only if it holds for the whole range. The same applies to reaching the head. “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

How the calculator works

A pump never delivers the maximum flow printed on the box: how much water actually arrives depends on how deep the water is, on the hose and on the pressure you need at the outlet. For each pump, the calculator finds the point where its curve meets the curve of your system.

How to use it

  1. Measure the depth of the water level and the height of the highest point the water has to reach, both from ground level.
  2. Enter the length and the internal diameter of the delivery hose.
  3. If you use sprinklers or emitters, enter the pressure given on their data sheet.
  4. Optional: the flow you need, which you can also work out with a bucket and a stopwatch.

Pumps are ranked by estimated flow, never by commission. For surface pumps we also check the declared maximum suction depth. How we do the sums is explained in where our data comes from; pressure loss in hoses is covered in the guide on pressure loss.

Sources

  1. Water - Dynamic (Absolute) and Kinematic Viscosity — The Engineering ToolBox, retrieved 11 Oct 2026
  2. Surface Roughness Coefficients — The Engineering ToolBox, retrieved 11 Oct 2026
  3. Explicit equations for pipe-flow problems — Swamee P. K., Jain A. K., Journal of the Hydraulics Division, ASCE, vol. 102, n. 5, pp. 657–664, maggio 1976 (scheda TRID), retrieved 11 Oct 2026
  4. JSW1 - JSW2 Elettropompe autoadescanti "JET" - 50 Hz — Pedrollo S.p.A., retrieved 11 Oct 2026
  5. JET - Elettropompe centrifughe autoadescanti, scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
  6. JETCOM - Elettropompe centrifughe autoadescanti, scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
  7. BG Series - Close-coupled self-priming centrifugal pumps, 50 Hz — Xylem (Lowara), retrieved 11 Oct 2026
  8. JEX Data Book 50Hz — EBARA Pumps Europe S.p.A., retrieved 11 Oct 2026
  9. Pompa da Giardino 5000 Silent — GARDENA, retrieved 11 Oct 2026
  10. 5000 Silent / 5200 Silent / 5400 Silent - Istruzioni per l'uso — GARDENA, retrieved 11 Oct 2026
  11. Einhell Pompe da giardino GC-GP 6538 — Einhell, retrieved 11 Oct 2026
  12. GC-GP 6538 - Istruzioni per l'uso — Einhell, retrieved 11 Oct 2026
  13. BP 3 Home & Garden - scheda prodotto — Kärcher, retrieved 11 Oct 2026
  14. Gartenpumpe GP 3000 INOX — T.I.P. Technische Industrie Produkte GmbH, retrieved 11 Oct 2026
  15. Gebrauchsanweisung Gartenpumpe GP 3000 / 4000 / 5000 INOX — T.I.P. Technische Industrie Produkte GmbH, retrieved 11 Oct 2026
  16. Istruzioni per l'uso pompa da giardino TGP 1000 E / TGP 1000 ES — Trotec, retrieved 11 Oct 2026
  17. GP 6035 93917 Originalbetriebsanleitung — GÜDE GmbH & Co. KG, retrieved 11 Oct 2026
  18. Pompa da giardino autoadescante acciaio inox 3800 l/h 1200 W max 48 m — WilTec Wildanger Technik GmbH, retrieved 11 Oct 2026
  19. Manuale articoli 51548 - 51551 — WilTec Wildanger Technik GmbH, retrieved 11 Oct 2026
  20. Pompa per cisterna 4000/1 — GARDENA, retrieved 11 Oct 2026
  21. Pompa per cisterna 4700/2 inox — GARDENA, retrieved 11 Oct 2026
  22. Regenfasspumpe / Tauchpumpe 4000/1, 4700/2 inox, 4700/2 inox automatic - Betriebsanleitung — GARDENA, retrieved 11 Oct 2026
  23. GE-SP 3546 RB - Istruzioni per l'uso originali — Einhell, retrieved 11 Oct 2026
  24. GE-SP 3546 RB - dati tecnici — Einhell, retrieved 11 Oct 2026
  25. GC-PP 900 N - Istruzioni per l'uso originali — Einhell, retrieved 11 Oct 2026
  26. Einhell GC-PP 900 N — Einhell, retrieved 11 Oct 2026
  27. BP 1 Barrel - scheda prodotto — Kärcher, retrieved 11 Oct 2026
  28. BP 2 per Cisterne - scheda prodotto — Kärcher, retrieved 11 Oct 2026
  29. Divertron - pompe sommerse multigiranti, scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
  30. Divertron - manuale d'istruzioni — DAB Pumps, retrieved 11 Oct 2026
  31. Nova - pompe sommergibili per acque chiare, scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
  32. TOP - elettropompe sommergibili da drenaggio, 50 Hz — Pedrollo S.p.A., retrieved 11 Oct 2026
  33. 4SR-S / 4SR - elettropompe sommerse da 4", 50 Hz — Pedrollo S.p.A., retrieved 11 Oct 2026
  34. S4 - elettropompe sommerse 4", scheda tecnica — DAB Pumps, retrieved 11 Oct 2026
  35. VEVOR pompa sommersa per pozzo 370 W, 110 l/min, prevalenza 44 m — VEVOR, retrieved 11 Oct 2026
  36. JET, JETINOX, JETCOM, AQUAJET, GARDEN-JET - Istruzioni per l'installazione e la manutenzione (60197625) — DAB Pumps, retrieved 12 Oct 2026
  37. BP 2 Cistern, istruzioni per l'uso originali (59910160, 02/22) — Alfred Kärcher SE & Co. KG, retrieved 12 Oct 2026
  38. BP 2 Cistern, istruzioni per l'uso originali (59661830, 08/13) — Alfred Kärcher GmbH & Co. KG; copia ospitata da media.hornbach.ch, retrieved 12 Oct 2026
  39. 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
  40. BP 1 Barrel, istruzioni per l'uso originali (59910220, 02/22) — Alfred Kärcher SE & Co. KG, retrieved 12 Oct 2026
  41. BP 3, BP 4, BP 5, BP 7 Home & Garden, istruzioni per l'uso originali (59910120, 01/22) — Alfred Kärcher SE & Co. KG, retrieved 12 Oct 2026