The primary objective of this preliminary study was to ascertain the concentration of endotoxin in a variety of Australian water types, including recycled water. A total of 42 sampling sites were surveyed, the majority on at least 2 separate occasions (total number of samples analysed was 76). Samples were collected from a variety of locations throughout Australia including: drinking water distribution (12), drinking water reservoir (4), wastewater treatment train (11) and finished recycled water (15). Class A recycled waters, defined microbiologically in Australian regulations as having <10 E. coli per 100 mL, where the treatment train did not include membrane filtration, gave rise to an average measured endotoxin concentration of 2.030 Endotoxin Units (EU) per mL (N=7). For recycled Class A water samples, where membrane filtration was part of the treatment train (N=3) the average endotoxin concentration was 41 EU/mL. Measured endotoxin concentrations in drinking water varied from <4 to 119 EU/mL. Results of this preliminary study indicate that endotoxin concentrations in recycled water may be reduced to levels at least as low as those found in drinking water but for some recycled waters, where membrane filtration is not practiced, higher endotoxin concentrations may persist.

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