Natural clarification of potable water in a semi-arid catchment

This paper examines the efficacy of the natural clarification system developed for potable water treatment in the semi-arid Leichhardt River catchment of north-west Queensland, Australia. The system is examined through its various stages. Sediment and water analyses show progressive improvements to water quality parameters such as turbidity, colour and heavy metal concentrations to within Australian Drinking Water Quality Guidelines. Tracked improvements to microbial water quality indicators (faecal coliforms and enterococcus) before chlorination emphasise the critical role that natural processes and regulated intakes perform in the protection of the potable water supply. The success of the system over the past 24 years, combined with its low cost and minimal maintenance has seen the CWL system viewed as a reliable method for improving water quality that has the potential to be modelled in other water supply catchments.