Private dams

Private dams

BASIX assesses private dams based on:

  • Catchment area - the areas diverted to the dam. Can include roof areas, pervious and impervious ground surfaces
  • Surface area and volume of the dam - in square metres and kilolitres

Private dams can be used to harvest water for toilet flushing, laundry, garden irrigation in single dwelling developments only, subject to relevant approvals and licences.

The dam nominated as an alternative water source for BASIX must be exclusively for household use. Water stored for agriculture, stock watering, firefighting or stormwater detention purposes cannot be included in this calculation.

For more information on private dams and the approvals and licence requirements for their construction, refer to advice provided by the NSW Office of Water.

Catchment area

The catchment area of the dam includes any diverted roof area, impervious areas, and the remaining pervious areas:

  • Impervious areas are surfaces that do not allow natural infiltration of rainfall to the underlying soil and include concrete, tiled and timber surfaces.
  • Pervious areas are surfaces that allow natural infiltration of rainfall to the underlying soil and include gardens, lawns, pasture and native vegetation stands.

Surface area and volume

  • Measure the surface area and volume of the dam when full. The area must be entered in square meters (m²).
  • The volume must be entered in kilolitres (note: 1 kilolitre = 1000 litres = 1m³).
  • Do not include water stored for agriculture, stock watering, firefighting or stormwater detention purposes in this calculation.

Measuring private dam size

Dam catchment areas, surface area and volume are required to complete the private dam calculations.

  • The catchment area of the dam includes any diverted roof area, impervious areas such as tiled areas and/or concrete driveways, and the remaining pervious areas which could include garden, lawns, pasture and/or native vegetation stands.
  • Measure the surface area of the dam when full.
  • All area estimates should be entered in square meters (m²).
  • Enter the volume of the private dam (when full) in kilolitres (note: 1 kilolitre = 1000 litres = 1m³).