Minimising risk to public health
Effective performance and management of sewage minimises risks to public health and the environment. On-site wastewater management systems collect, contain, treat and assimilate and process wastewater, human excreta, or both, so that public health and environmental standards are achieved.
Performance and management requirements will vary depending on:
- the source of the wastewater or human excreta
- the method of treatment
- effluent quality required for the end uses of the treated water
Different treatment levels
There are generally three levels of treatment:
- primary treatment
- secondary treatment
- disinfected secondary treated
Wastewater treatment units providing primary treated effluent are only suitable for:
- in-ground application by soil absorption in trenches, mounds or evapo-transpiration absorption
- seepage beds and trenches
Wastewater treatment units providing secondary treated effluent are suitable for:
- application to land by covered surface drip systems
- application to land by shallow subsurface drip systems
Wastewater treatment units providing disinfected secondary treated effluent are suitable for:
- all of the above methods of application
- above ground application by spray irrigation
Wastewater treatment units, treating greywater only, providing disinfected advanced secondary treatment quality, are suitable for:
- surface spray irrigation
- toilet flushing
- cold water used for washing clothes in a washing machine
Waterless composting toilets (WCT) are an acceptable means of treating human excreta only. Treated waste from a WCT may be buried on-site where direct access is restricted.
All the above options for end uses of the treated wastewater are subject to the consent of the permit authority (council).
Management of on-site wastewater management systems in Tasmania
In Tasmania, the installation of on-site wastewater management systems is managed as follows:
- The Director of Building Control assesses the results of performance testing of each treatment technology. Where satisfied that the technology meets the appropriate standard, a Certificate of Accreditation will be issued (with conditions), allowing the system to be installed and used.
- The permit authority considers applications to install or alter on-site wastewater management systems. The permit authority needs to be satisfied that the proposed system is likely to be installed and used in accordance with the conditions of accreditation.
- Systems which are purpose built for a particular site and not offered for sale, do not require accreditation and are dealt with by the permit authority. This includes conventional septic tank installations.