On-site wastewater treatment systems (OWTS) are widely used in Western Australia (WA) to treat and dispose of household wastewater in areas where centralized sewerage systems are unavailable. Septic tanks, aerobic treatment units (ATUs), and composting toilets with greywater systems are among the most well established and commonly used OWTS. However, there are concerns that some OWTS installed in WA are either performing below expected standards or failing. Poorly performing OWTS are often attributed to inadequate installation, inadequate maintenance, poor public awareness, insufficient local authority resources, ongoing wastewater management issues, or inadequate adoption of standards, procedures, and guidelines. This paper is to review the installations and failures of OWTS in WA. Recommendations to the Department of Health Western Australia (DOHWA) and Local Government (LG) in regard to management strategies and institutional arrangements of OWTS are also highlighted.

Water recycling schemes have been in operation in Western Australia since 1960. As a requirement of the regulatory framework for wastewater reuse, periodic water quality monitoring has been implemented to demonstrate microbial compliance for the intended end-use. For this study, we originally planned to analyse the compliance of the 92 water recycling schemes in the database over a seven-year period (2003-2009), however it was necessary to exclude 21 schemes because they either lacked sufficient data or their recording standards were too inconsistent for the analysis. Compliance was analysed by comparing: i) the observed microbial results against the quality criteria and, ii) the number of samples analysed against the expected number of samples based on regulatory frequency requirements. The results indicate that 12% of the remaining 71 schemes analysed did not comply with water quality criteria over the seven-year period and most of the original 92 recycling schemes did not comply with the expected number of samples. Challenges faced by existing schemes in conforming to the Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1) (2006), and the Guidelines for the Non-Potable Uses of Recycled Water in Western Australia (2011) are discussed.

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