A review of the 19th century and early 20th century literature reveals that a largely correct picture of the role of many microalgae as sources of tastes and odours in water supplies had been obtained by the end of the 19th century. Attention was not paid to actinomycetes as an odour source until the end of the 1920s. Scientific studies on the etiology of off-flavours in fish began in 1910, revealing an essentially modern picture from the beginning.