When you rely on a cistern for indoor water, the electric pump acts as the mechanical heart of your house. When it fails, the house immediately stops functioning. Fortunately, 90% of pump issues are completely solvable without calling a plumber if you understand the basic physics of how they operate.
Problem 1: The Pump Won't Turn On
You flush the toilet, the pressure vessel empties, but the pump never kicks on to refill it.
- Run-Dry Protection: Modern high-quality pumps have "run-dry" sensors. If your tank is empty, or the water level dropped below the intake so the pump sucked in a giant gulp of air, the sensor will instantly cut the power to prevent the motor from burning up. Check your tank level. If you have water, you may need to manually press the "Reset" button on the pump controller.
- Blown Breaker or GFI: Pumps draw a large surge of electricity upon starting. Ensure the breaker hasn't tripped, and reset the GFI outlet the pump is plugged into.
Problem 2: The Pump Rapidly Clicks On and Off
Usually accompanied by a rapid "chattering" or "machine gun" sound from the pipes.
- Lost Air Charge in Pressure Vessel: The most common cause. The expansion tank uses compressed air behind a rubber bladder to act as a shock absorber. Over the years, this air can slowly leak out of the Schrader valve on top. Without a cushion of air, water pressure spikes violently, tricking the pump into turning on and off multiple times a second. You must drain the system and use a bicycle pump or air compressor to re-pressurize the tank to its factory spec (usually 2 PSI below the pump's cut-on pressure).
- Ruptured Bladder: If you press the little pin on the air valve of the pressure vessel and water shoots out instead of air, the internal rubber has ruptured. The entire pressure tank must be replaced.
Problem 3: The Pump Won't Turn Off
The pump runs continuously, even when all the faucets and toilets in the house are closed.
- A Massive Leak: The pump is trying to reach 60 PSI, but water is escaping the system so fast it can't build pressure. Check for a burst pipe, an outdoor spigot left wide open, or a toilet where the flapper is completely jammed open.
- Clogged Intake: The pump is running, but it's starved for water. If the pre-filter is completely clogged with mud, or the floating intake inside the tank is blocked by debris, the pump simply can't pull enough water to build pressure and satisfy the controller. Clean the filters.
- Failed Pressure Switch: The electronic or mechanical switch that tells the pump it has reached 60 PSI has broken, forcing the pump to run forever. You will need to replace the pressure switch or controller unit.
Problem 4: Loss of Prime
For surface pumps sitting next to the tank (not submersible pumps inside the tank), they must have water in the suction line to work. If air entered the suction line (due to a loose fitting or the tank temporarily running dry), the pump will spin wildly but move no water, because centrifugal pumps are terrible at pumping air. You must open the priming port on top of the pump, manually pour water in with a pitcher until it overflows, seal it, and restart it to re-establish the suction vacuum.