Common Causes of Water Pump Life Reduction and/or Water Pump Component Failure

For water trucks with hydraulic driven and direct driven water pumps by far the most common cause of premature wear and ultimate failure of the water pump and surrounding components is due to high energy engagements and disengagements i.e. engagements and disengagements at high engine RPM. 

The Water Pump is a critical component on any water truck and failure of this component can lead to the water truck being ineffective and in some cases bringing the complete earthmoving operation to a halt.  So focus should be on preventing a water pump failure


The water pump shaft is one of the most highly stressed areas  on any centrifugal water pump and there is several areas that contribute to any failure and we will outline steps that can be taken to reduce a chance of a failure


Contributing Factors

  • Material Flaws 

Unfortunately often only identified after a failure 

  • Misalignment
    • PTO to Water Pump
      • Should be slightly offset up to a maximum of 15 degrees (not directly in line) - the universal joints must be engaged in working and will compensate for any misalignment 
    • Hydraulic motor to Water Pump
      • Close coupled - where hydraulic motor mounts directly to the water pump and mounting will be only the water pump
      • Directly inline and fitted with a cushion coupling/joiner (Often a mounting frame must be built for each individual water pump and hydraulic motor)
        • If the hydraulic motor is slightly offset to the water pump the life of the coupling will be vastly reduced

Care must be taken when fitting a water pump and aligning a drive system if it is not a close coupled system


  • Vibration
    • Often caused by cavitation,  operating at excessive RPM, or impeller imbalance.  


  • Water Hammer 
    • Often caused by sudden shut off or sudden stopping of water flow

It is often good practice to install a relief valve in the pressure piping to reduce any excessive system pressure this can also limit flexible hoses ‘blowing off’.


If you need any help or have any questions at all please don’t hesitate to contact  the Water Wise Team on 1300 306 917 or


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