Waste Water

Properties located in areas within the Shire of Denmark that don’t have deep sewer are required to install onsite effluent disposal systems.

The first step is to contact Water Corporation to determine whether deep sewer is available.

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For residential properties using less than 540L/day and housing not more than eight people, an application to construct or install an apparatus for the treatment of sewage must be made to the Shire for approval to install the system.

Several systems can be chosen from; however, the system must meet the required environmental conditions and volume capacity. For more information on the different types of systems please refer to the Department of Health WA website or contact a licensed plumber for advice.

Once the system has been installed, the plumber must lodge an ‘As Constructed Diagram' with the Shire of Denmark.

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Effluent disposal for larger residences or commercial premises requires approval from the Department of Health.

The Shire accepts the fee and application form on behalf of the Department of Health.  The application is submitted to the Department of Health along with a supporting report prepared by the Shire. Please contact the Department of Health WA for guidance on the application and approval of a commercial system.

The application must be submitted, and approval received before installing the system. A Permit to Use must be obtained prior to using the system.

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When Decommissioning is Required

When mains sewage becomes available to a property, the owner has five years to disconnect the onsite disposal system and connect to sewer. Decommissioning is only required by law when:

  • There is a change in use of the premise, or
  • Within 60 days of change of ownership of a property, or
  • Extensions to the property encroach on setback requirements for the systems.
How to decommission a septic tank

Decommissioning means that the contents of the tanks are pumped out and the system is either removed or back filled. This is to prevent these from collapsing and possibly causing damage. Only licensed and approved personnel can decommission septic tanks.

Proof of decommissioning

Property owners are encouraged to retain copies of any receipts and take photos of the decommissioning work. New property owners are responsible for ensuring that septic tanks are decommissioned and are advised to obtain proof.

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Useful Links


Our Environmental Health Officer can assist with queries related to waste water on 9848 0300 or enquiries@denmark.wa.gov.au.

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