Wastewater & Greywater

Septic tank systems

Unsewered properties within the City of Kalgoorlie-Boulder require septic tanks to treat and dispose of sewage and wastewater.

Constructing a septic tank system

Depending on the development, approval to construct a septic system must be sought from either:

  • City of Kalgoorlie-Boulder
  • Chief Health Officer at Department of Health

The City’s Environmental Health Services will advise you whom to seek approval from.

Please download and complete the Washdown Bay fact sheet and application which must be accompanied by:

  • Two sets of detailed plans (1:100 or 1:200 scales only)
  • Relevant fee
  • Application form
  • Information on plan drawings, submissions and approval process
  • Fees and payments

Please note: Approval to construct a septic tank system is separate from approval to use the system.

In order to receive approval to use the system, the City must conduct an inspection to ensure it is installed correctly.

Decommissioning a septic tank system

If a property is connected to the sewer system, the disused septic tank system can be decommissioned. Owners are not required to have the disused system decommissioned at the time of sewer connection.

Decommissioning is only required when:

  • The property is sold
  • The use of the development changes (such as from a residence to a business)
  • Building extensions encroach on the minimum setbacks from the system

Decommissioning involves pumping the contents out of the tanks and removing the entire system, where possible.

If it is not possible to remove the whole system, then the base of the septic tanks must be broken and the entire system backfilled with clean soil.

For more information download the Decommissioning of a Septic Tank fact sheet.


Greywater refers to all non-toilet household wastewater. It can be reused in domestic settings, especially during periods of drought or water restrictions. Doing so has some health and environmental risks.

The following tips will improve the health and safety of greywater reuse:

  • Only reuse water from baths, showers, hand basins and washing machines (final rinse)
  • Only use greywater on gardens, and rotate the areas you water
  • Only use as much water as the soil can absorb
  • Thoroughly wash your hands after using greywater

Do not use greywater:

  • During wet periods
  • If odours are produced and plants appear unhealthy
  • To water vegetables that are to be eaten raw or uncooked
  • That is contaminated—for example, water used to wash nappies
  • From the kitchen (including dishwashers)—the high concentration of food waste and chemicals are not readily broken down in the soil
  • That has been stored for more than 24 hours


  • Do not let children or pets drink or play with greywater
  • Do not allow greywater to flow from your property or enter stormwater systems

Greywater systems

If you wish to put in a permanent system for greywater reuse, you will need to apply to the City of Kalgoorlie-Boulder for approval.

Evaporative Air Conditioning Bleed-off

For information on evaporative air conditioners, download our Evaporative Air Conditioning Fact Sheet.

More Information

The WA Department of Health website contains information on wastewater management, including:

  • Septic tanks
  • Aerobic treatment units
  • Decommissioning
  • Greywater
  • Code of Practice
  • Product approvals
  • Domestic wastewater overflows

Quick Links

WA Department of Health

Domestic wastewater overflows

Wastewater Application

Decommissioning a Septic Tank fact sheet

Evaporative Air Conditioning Fact Sheet