Taste and odour threshold concentrations of potential potable water contaminants

Taste and odour complaints from consumers are a major problem for suppliers of drinking water. Small quantities of chemicals, either naturally present in raw water or from industrial sources, or even produced during water treatment, can affect the organoleptic properties of drinking water. Taste and odour threshold concentrations in water were determined for 59 potential drinking water contaminants, including pesticides, phenol, chlorinated phenolic compounds and anisoles, geosmin, 2-methyl-isoborneol and aluminium sulphate. Panels comprising a minimum of six specially selected and trained assessors were used. Taste and odour threshold concentrations are presented as geometric means as well as the lowest detected concentration; in addition, descriptors are reported. Threshold concentrations are also compared with health-based limits established by the United States Environmental Protection Agency, and drinking water guideline values recommended by the World Health Organisation. The results indicated that there was no correlation between organoleptic effects of drinking water contaminants and their toxicity. Chemicals with the lowest taste and odour threshold values included chemicals such as geosmin, 2-methyl-isoborneol and similar microbial metabolites, and chlorinated phenols and anisoles.