Farm Water Calculator: the annual balance


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Total Farm Water

The Farm Water Balance

During periods of low rainfall, dams and farm catchments receive limited run-off and creeks can run dry. Dam and tank water then becomes a limited resource. The Farm Water Balance is a calculation that compares the Water Storage on-farm (dams and tanks) to the water use on-farm over a year. It is a useful calculation where water supply is intermittent.

Farm Water Balance = Water Storage on-farm - Water use on-farm
Farm Water Balance = No Value set  - No Value set
Farm Water Balance = 0 megalitres/year


A surplus means that the volume of storage available is more then the amount of water required on-farm for a year. Providing the storages are full at the start of the year, the yearly water requirement for the property can be met.


A deficit means that the annual water requirement has exceeded the storage available on-farm. If the Water Balance is a deficit the following should be considered;

  • Does the water source (potential water supply) provide frequent refilling of the storage so the property does not experience an actual water shortage in most years, or,
  • There is sufficient water available, in some years, but not others, and it occasionally runs out of water, or
  • The property regularly runs short of water on an almost annual basis.