Self-Priming Pumps

How a self-priming pump works

A self-priming pump expels the air in its suction line on its own, fills up and starts delivering. That is what sets it apart from a plain centrifugal pump, which has to be primed by hand and loses its prime the moment it draws air. It is the right choice whenever the pump sits above the water level: a well, a buried tank, a rainwater butt, a watercourse.

The first prime is still manual: you fill the pump body before the very first start. After that it re-primes itself following a stop, as long as the foot valve stays tight.

Suction lift: the physical limit

Whatever the pump, suction relies on atmospheric pressure: beyond roughly 8 metres between the pump and the water surface, no surface pump will lift at all, and the figure falls further with altitude, water temperature and friction losses in the line.

If your water level sits lower, you need a borehole pump, not a surface pump. Measure the level while pumping, not at rest: a well often drops several metres once drawdown starts.

The range: 230 V single-phase and 380–400 V three-phase

Our self-priming jet pumps run from 0.55 to 1.65 kW. Single-phase 230 V covers almost every domestic and agricultural use. Three-phase suits sites that already have it: better efficiency and steadier torque at higher powers, but it needs the matching supply.

• 0.55 to 0.75 kW: irrigation, feeding one outlet, a small tank.
• 1.1 kW: a house, garden irrigation, transfer between tanks.
• 1.65 kW three-phase: agricultural or commercial duty, longer pipe runs.

The selection method is set out in our self-priming pump guide, including how to calculate total head.

What to measure before ordering

• Working flow rate in m³/h — not the catalogue maximum.
• Suction lift between the pump and the water level while running.
• Discharge height and pipe length, which create the friction losses.
• Connection sizes and the nature of the water: clean, turbid, acidic, brackish.
• Supply available: 230 V single-phase or 380–400 V three-phase.

Self-priming, booster set or centrifugal?

A self-priming pump lifts water. A booster set regulates pressure and starts on its own thanks to its vessel and pressure switch. A centrifugal surface pump shifts high flow at low head but must stay flooded. The first two are often combined: a self-priming pump draws from the well, while a vessel and switch hold pressure in the house.

Frequently asked questions

Request a pump sizing