My Well Pump Has a Problem Holding Prime

Above ground well water pumps must contain water in the suction line.

Inspection and Testing

Failure of the system to hold water in the suction line causes the pump to cavitate with air. Air in the suction system of the pumping chamber forces the pump to work harder and may cause premature failure to the internal water seals. All above ground well water pumps use a foot valve to hold the suction line full of water. Failure of the foot valve is one reason for a pump to lose the prime.

Point the flashlight down the well. If the surface of the water is above the lower end of the suction pipe, the well has plenty of water. If the end of the suction pipe is exposed, showing the brass colored foot valve, the well is dry and must have time to recover. A dry well draws air into the suction pipe causing a loss of prime.

Fit the jaws of the plumbers pliers over the square neck plug at the top of the pumping chamber. Turn the pliers in a counterclockwise direction. Remove the plug to prime the pump.

Fill the chamber and the suction pipe with water. Shine the flashlight down the well casing. Observe the suction pipe for signs of water leaking from the suction pipe joints. If water is seeping from the pipe joints, prime is being lost in the suction system.

Add water to fill the pumping chamber and the attached suction pipe. If the chamber never fills with water, the foot valve is being held open by debris or has failed in the open position.

Foot Valve Replacement

Shut off all electrical power for the well pump circuit.

Disconnect the suction line from the well pump. Various well pump installations will have different methods of removing the suction line from the well pump chamber. Follow the instructions for your make and model of well pump for the suction line removal.

Pull the suction line from the well casing or opening. You may require a helper when pulling the suction line from the well. Lay the piping on a flat surface. In most cases of foot valve failure, the suction line will be void of water.

Fit the jaws of one of the pipe wrenches over the suction line near the foot valve connection to hold the pipe in place. Tighten the jaws of the second pipe wrench over the brass fitting of the foot valve. Turn the second pipe wrench in a counter clockwise direction to loosen the foot valve. Remove the device from the suction line.

Apply two or three rounds of the thread tape over the male threads of the suction pipe. Screw the replacement valve onto the suction pipe in a clockwise direction. Tighten the valve with the pipe wrench. Install the suction pipe and new foot valve into the well. Attach the suction pipe to the well pump. Prime the suction line and pumping chamber. Switch the power back on to the well system.

Things You Will Need

  • Flashlight
  • Plumbers pliers
  • Helper (optional)
  • 2 pipe wrenches
  • Pipe thread tape
  • Replacement foot valve

Tip

  • Excessive operation of the water pump without water will ruin the pumping mechanism and burn the internal rubber seals. You may need to shock chlorinate the well after servicing.