Wastewater disposal

Wastewater disposal and systems 

Effective wastewater disposal is very important to public health and safety. The City can help you secure the required approvals for your proposed wastewater disposal system.  

Onsite wastewater systems include septic tanks, aerobic treatment units (ATUs), waste water treatment plants and wash down pads. Onsite disposal of wastewater is required where reticulated sewerage is unavailable.  

All applications must be lodged to the City of Karratha in the first instance. If it is intended that the proposed apparatus will handle less than 540L/day of wastewater, or the building to be serviced is a single dwelling, the City will process your application.  

If the wastewater volume generated is more than 540L/day and the building being serviced is not a single dwelling, the City will assesses your application, prepare a local government report and forward the application to the Department of Health for consideration. 

Greywater disposal 

Treated greywater can be used for a variety of different end uses, such as irrigating gardens or flushing toilets. Reuse of greywater is supported and encouraged by Government to help conserve water. However, this has to be accomplished without compromising public health, causing unacceptable environmental impact, or downgrading the amenity of our residential areas.  

Pathogenic microorganisms can be present in greywater at levels high enough to pose a health risk. Therefore a level of caution must be exercised with greywater reuse. The health risk associated with greywater reuse can be minimised by not allowing human contact with untreated greywater, or by treating the greywater to an appropriate quality for its intended end use.   

The Code of Practice for the Reuse of Greywater in Western Australia 2010 is the basis on which greywater reuse applications are assessed. The Code sets the minimum requirements for the reuse of greywater in sewered areas of Western Australia on: 

Single residential domestic premises 

Multiple dwellings producing up to 5000L/day of greywater 

Commercial premises reusing up to 5000L/day.  

Local government is responsible for the approval of all greywater systems used in single dwellings. For multi-dwelling and commercial premises, the Code defines the responsible agency (i.e. local government or the Department of Health WA) that will approve the greywater reuse system based on treatment method, proposed end uses and estimation of volumes of greywater produced (see section 5: Approvals required for greywater reuse)

Lodging an application to install a wastewater system 

Complete an application form to install a wastewater system, including site plans to scale. Your plans should include:  

Location of wastewater system including drains and pipe work 

Location of any buildings on the property; 

Distance from buildings, boundaries, bores, waterway and water bodies; 

Location of trafficable areas; and 

Contours to indicate slope of the land. 

An Environmental Health Officer will contact you to arrange assessment of the system according to legislative requirements.  

Visit the Department of Health website for more information on wastewater legislation and guidelines.   

Once your wastewater system has been installed, and before the system is backfilled, contact an Environmental Health Officer to arrange a final inspection of the installation.  

Following this inspection, and the submission of a Certificate of Compliance from the Plumbers Licencing Board to the City, you will be issued with a permit to use the system. 

Should you wish to install a system for the reuse of grey water, information in this regard can be found on the Department of Health website - Code of Practice for the Reuse of Greywater in Western Australia document. 


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