Potable reuse: Which chemicals to be concerned about

The growth of potable reuse as a planned water supply strategy has led to an increased focus on the presence and significance of trace chemical contaminants. By the use of reclaimed wastewater as a source, potable reuse projects require serious consideration to be given to the range and character of chemicals which may be present and may pose unacceptable risks to public health if not properly managed. The first step, required to assess and manage risks, is to consider the range of chemical contaminants which may be present. Although it is impossible to derive an exhaustive list, it is useful to consider broad categories and the specific types of challenges that may be posed by the chemicals within those categories. Such a broad categorisation of chemical contaminants is presented in this review and provides the basis for initial consideration by those tasked with assessing the water quality and treatment requirements of a potable reuse project. Chemicals, which may potentially be of concern in potable reuse projects, are diverse in terms of their (anthropogenic or natural) source, chemical characteristics and their likely human toxicity. Public health risk assessments are further complicated by the inevitable presence of unidentified chemicals and potential impacts of ‘mixture effects’ on the overall toxicity of complex, low-concentration chemical mixtures.