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Recycled Water for Drinking

Chemicals can act together in mixtures, especially when they exert the same mode of toxic action. Wastewater, and to a minor extent recycled water, are complex mixtures containing an unknown number of components; the effect on cells and vital function caused by exposure to these complex mixtures was investigated in this study.

This project focused on micropollutants (pesticides, pharmaceuticals, etc.) rather than macropollutants (nitrogen, phosphorous, salts, etc.) to evaluate the effects of mixtures of chemicals and the unintended transformation products formed during disinfection processes. The work plan considered four questions

1. Do mixtures matter?

Involves toxicity assessment for complex mixtures

2. How much of the iceberg do we see?

Involves toxicity experiments of defined mixtures and analysis of regulated chemicals in recycled water

3. Do transformation products contribute?

Involves a novel tiered approach for screening micropollutants for their potential to form toxic transformation products

4. How much do we really know and do we monitor the right thing?

Involves synthesis of the outcomes from work plan questions one to three and a proposal on how to perform a tiered micropollutant assessment

Greater than 99.9 per cent of the toxic effects of wastewater are caused by unknown chemicals in a sample. Bioanalytical tools that target specific mechanisms of toxicity irrespective of chemical source can give a measure of the cytotoxicity of all chemicals acting together in a water sample, even when concentrations of individual chemicals are below the limit of detection.

A systematic screening method using cell-based assays was developed for assessing risks posed by newly formed transformation products; if toxicity increased during a transformation process we attempted to identify the causative agent. The knowledge generated is available to support future policy and regulatory decision-making and make a significant contribution to chemical risk assessments of recycled water.


This project aimed to lead to a new approach for monitoring micropollutants in water samples by looking at effects as a sum parameter rather than measuring individual chemicals. More cost-efficient and targeted assessment tools could then be developed and used by regulators, industry and utilities to help ensure water quality, and incorporated into water quality management guidelines for water recycling schemes by state health regulators.

Compounds with high potential to form toxic transformation products were identified through a rigorous literature review and experimental testing.

The project’s final report synthesised the outcomes from all previous work packages  and  provides important insights on appropriate toxicity monitoring priorities for recycled water.



Lead organisation: National Research Centre for Environmental Toxicology (ENTOX), The University of Queensland
Partner organisations: WA WaterCorp
WA Department of Health
Queensland Department of Energy and Water Supply
Queensland Health
Water Research Australia (formerly Water Quality Research Australia)
Veolia Water

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