3 Main Culprits of a Water Pump That Runs but Doesn't Pump Water

20 May 2019
 Categories: , Blog


Owning a water pump in rural Australia is one of the easiest ways to source water. From watering cattle to domestic use, pumping water from underground sources is critical in areas that do not have a connection to the mains. However, you can only benefit from your pump if it is running in optimal condition. That said, water pumps can develop problems with one of the main ones being the inability to pump water even though the pump's motor is running. This article looks at the possible culprits in such a situation.

Not Filling Primer Cap

Some water pumps are self-priming while others have to be primed before pumping water. It means that water must first fill the cap before the pump can start pumping water. A water pump with a self-primer will fill the primer cap automatically once the pump is turned on. However, if your water pump requires manual priming, then it will not pump water even when powered on. It is because the pump is still filled with air which does not allow water through once the pump is powered on. Therefore, if your pump is running but not pumping water, ensure that you fill the primer cap with water manually. It will create a vacuum, thereby drawing water.

Worn Impeller

Ideally, the impeller is the fan that rotates inside the pump as it pumps water. In a new or well-maintained pump, the fins of the impeller work fine and allow the machine to pump water at full capacity. However, the problem arises when the fins wear out or get damaged by unfiltered water and are not replaced in time. In either case, the pump will still run as usual, but the worn-out or damaged impeller fins will not pump water at full capacity. Open your pump's housing and inspect the impeller for possible wear or damage and replace it if necessary.

Broken Drive Shaft

It is the part that connects the motor to the pump, and its rotational energy gives the machine the necessary power to pump. While the driveshaft and its connections are made of robust material, the shaft can still break or fail, and the pump will no longer manage to pump water. Notably, the water pump will still run with a broken driveshaft. If you hear clunking noises inside the pump casing as the pump runs, then it might be a sign of a broken drive shaft. You can, however, only ascertain the breakdown by inspecting the part physically. Notably, most broken water pump drive shafts can be welded back and still run efficiently.

Reach out to a water pump repair technician to learn more.