Description
The Pentax 3S 3-15 (code 022-920) is the entry model in the Pentax 3S range of 3-inch multistage borehole pumps. Its 15 impellers deliver up to 45 litres per minute and a maximum head of 46 metres from a 0.33 kW (0.5 HP) motor on 230v single-phase, through a 1″ G outlet.
It is the pump to choose for a shallow 3-inch bore where the water sits close to the surface and you only need modest pressure at ground level. At 20 l/min it gives about 36 metres of head, and at 30 l/min about 28 metres. If your water level is deeper or you want more pressure at the tap, the Pentax 3S 3-23 adds eight more impellers and reaches 70 metres.
The pump end has a stainless steel shell, pump shaft and coupling, Noryl impellers and self-lubricating polyacetal diffusers, with a 1″ G threaded outlet. Pentax drives it with a 2-pole asynchronous submersible motor with class F insulation and IP58 protection.
Features
- 15 impellers, maximum head 46 m, maximum flow 45 l/min
- About 36 m of head at 20 l/min and 7 m at 45 l/min
- 0.33 kW (0.5 HP) motor, 230v single-phase
- Made for 3-inch wells and boreholes
- Stainless steel shell, shaft and coupling
- Noryl impellers and self-lubricating polyacetal diffusers
- 1″ G threaded outlet
- IP58 motor, class F insulation
Applications
- Garden and allotment watering from a shallow borehole
- Topping up storage tanks and water butts
- Small domestic water supplies with a header tank
- Replacing a pump in an older 3-inch bore
The 3S 3-15 is for clean water only, with no more than 40 g/m³ of sand. It is not a dirty water or drainage pump and must never run dry, so Pentax recommends level probes to switch it off if the water level falls. It is made for 3-inch wells; in a much wider bore, fit a cooling jacket so water flows past the motor.

The Pentax 3S range
| Model | Impellers | Supply | Motor (kW) | Max Head (m) | Head at 20 l/min (m) | Head at 45 l/min (m) | Code |
|---|---|---|---|---|---|---|---|
| Pentax 3S 3-15 | 15 | 230v single-phase | 0.33 | 46 | 36 | 7 | 022-920 |
| Pentax 3S 3-23 | 23 | 230v single-phase | 0.55 | 70 | 55 | 13 | 022-922 |
| Pentax 3S 3-30 | 30 | 230v single-phase | 0.75 | 92 | 73 | 17 | 022-924 |
| Pentax 3S 3-45 | 45 | 400v three-phase | 1.1 | 128 | 103 | 28 | 022-926 |
All four models are rated to 45 l/min with a 1″ G outlet. See the Pentax 3S 3-inch borehole pumps page for help choosing between them and answers to common questions.









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