A Gram-staining-negative, aerobic to microaerophilic, rod-shaped, red-coloured bacterium, strain T4(T), was isolated from a freshwater pipe on Tenerife island. A polyphasic taxonomic study was performed in order to characterize the strain in detail. The isolate is surrounded by a slime capsule, occurs singly, in the form of short chains, or in aggregates, and exhibits catalase and oxidase activities. Growth was observed at 15-42 °C. Optimum growth occurred at pH 8 with mono- and disaccharides, followed by polysaccharides and deoxysaccharides, but the bacterium utilized only a restricted spectrum of alcohols, alditols, amides, amines, carboxylic acids and amino acids. Strain T4(T) tolerated concentrations of 0-4% (w/v) NaCl and contained MK-7 as predominant isoprenoid quinone as well as carotenoids, but lacked pigments of the flexirubin type. The predominant fatty acids were iso-C(15:0) (32.2%), summed feature 3 (C(16:1)ω6c and/or C(16:1)ω7c; 22.5%), and iso-C(17:0) 3-OH (7.9%). Major polar lipids were phosphatidylethanolamine, phospholipids, aminophospholipids and other lipids of unknown character. The DNA G+C content was approximately 41.8 mol%. The sequence of the 16S-rRNA gene assigned strain T4(T) to the CFB group, forming a coherent cluster with species of the genus Algoriphagus with the highest similarity of 98.8% to Algoriphagus aquatilis A8-7(T). DNA-DNA hybridization revealed 37.5% relatedness to strain A8-7(T). Based on morphological, physiological and molecular properties as well as on phylogenetic distinctiveness, strain T4(T) should be placed into the genus Algoriphagus as a novel species, for which the name Algoriphagus aquaeductus sp. nov. (type strain T4(T) =DSM 19759(T) =LMG 24398(T) =NCIMB 14399(T)) is proposed.