A review of on-site wastewater practices in south-east Queensland

Abstract

This paper presents results from a 'census' of the status of on-site wastewater treatment systems (OWTS) management practices in the SEQ region as part of the Healthy Waterways initiative. The current number of on-site systems is estimated to be 127,000 with septic systems accounting for 80%. Key management issues were highlighted during the project, notably the frequency of greywater failure and inappropriate greywater discharge. Septic system failures were reported mainly in the newer combined septic systems that receive 100% of household water compared with the split blackwater systems that receive about 20%. Aerated systems were inadequately maintained. However, to date, no "smoking guns" of poor water quality from non-sewered catchments have been clearly identified. A clear outcome of this survey was the need for all SEQ Local Authorities to audit every on-site system. Predictions and assessment of catchment water quality risks from on-site systems would be greatly facilitated if data obtained from these audits could be used in catchment water quality modelling and risk assessment.