A polyphasic taxonomic study was carried out on 2C1-b(T) and 2C-21, two strains isolated from sewage flowing into River Geumho in Korea. Cells of the two strains were Gram-negative, non-spore-forming, motile and oval or rod-shaped. Comparative 16S rRNA gene sequence studies showed a clear affiliation of these two isolates with members of the Betaproteobacteria; they were most closely related to Variovorax boronicumulans KCTC 22010(T), Variovorax dokdonensis KCTC 12544(T), Variovorax ginsengisoli KCTC 12583(T), Variovorax paradoxus ATCC 17713(T) and Variovorax soli KACC 11579(T) showing 16S rRNA gene sequence similarities of 97.4-98.8% with these strains and shared 100% similarity with each other. The genomic DNA G+C contents of strains 2C1-b(T) and 2C1-21 were 65.5 and 65.2 mol%, respectively. Phenotypic and chemotaxonomic data [Q-8 as the major ubiquinone; C(16:0), summed feature 4 (C(16:1)ω7c and/or iso-C(15:0) 2-OH), C(17:0) cyclo and summed feature 7 (C(18:1)ω7c and/or ω9t and/or ω12t) as major fatty acids] supported the affiliation of strains 2C1-b(T) and 2C-21 to the genus Variovorax. Based on evidence derived from this polyphasic analysis, it is proposed that strains 2C1-b(T) and 2C1-21 represent a novel species for which the name Variovorax defluvii sp. nov. is proposed; the type strain is 2C1-b(T) ( = KCTC 12768(T) = JCM 17804(T)).