The author wishes to inform readers that a reference cited in the above article has been updated.

The reference in question is: ‘ISO 2002 Water Quality Detection and enumeration of Clostridium perfringens. Part 2: Method by membrane filtration (revision of ISO 6461-2:1986). Committee draft ISO/CD 6461-2. International Organization for Standardization, Geneva’.

The corrected reference, submitted to the author by Regina Sommer, convener of the ISO working group, is: ‘ISO 2013 Water Quality—Enumeration of Clostridium perfringens—Method using membrane filtration (ISO 14189: 2013). International Organization for Standardization, Geneva’.