The pump switches on and the motor hums, but no water comes, or it comes in spurts. Usually the pump itself is fine: a surface pump cannot draw air, and any gap in the suction line starves it of water. Check things in order, from the source to the pump.

What the diagram shows

1 — a foot valve with a strainer on the end of the suction pipe, 2 — a loose joint where the pump draws in air, 3 — the pump’s priming plug, 4 — a pressure gauge.

What to check

  1. Is there water in the source? In summer and after long use the water level in a well drops. If the end of the pipe is above the water, the pump is drawing air. Lower the pipe, or wait for the well to refill.
  2. Is the pump primed? Before the first start, and whenever the system has drained, fill the pump body and suction pipe with water through the priming plug until it overflows. A surface pump cannot lift water without this.
  3. Does the foot valve hold? If water runs back into the well after the pump stops, the pump has to start from scratch every time. Pull up the pipe and check the valve and strainer: silt often clogs them, or a grain of sand jams the valve. See “Check valves”.
  4. Is there an air leak? Bubbles in a clear section of pipe, spluttering water and pressure that never builds are signs of air getting in through a thread or a crack. Tighten the joints and check the pipe along its whole length.
  5. Is the water too deep? A surface pump usually lifts water from no deeper than 7–8 m, and that includes the resistance of any horizontal run of pipe. If the water is lower, you need a submersible pump or a pump with a remote ejector.

If the pump only hums and does not turn

A motor that hums without turning has either seized after standing idle or has a failed start capacitor. Switch it off at once: in this state the winding overheats within minutes. Have an electrician or a service centre check the capacitor and motor.

Never let a pump run without water: dry running quickly wears out the seals and the impeller. Dry-run protection can be fitted separately — it switches the pump off when the water runs out.

If the pump delivers water but starts too often, see “Pump keeps switching on and off”. Check valves, pressure switches and dry-run protection are in pump controls.