Treatment of groundwater by Bioactive Granular Activated Carbon (BioGAC) filtration is used to decontaminate chloroethene-contaminated groundwater. In the present study, the vinyl chloride (VC) aerobic degradation potential and the community composition of BioGAC microbiota of four BioGAC reactors were studied. Upon incubation with VC, the microbiota from BioGAC reactors receiving VC-contaminated groundwater (2.7 - 49 µg L -1 ) depleted VC after a lag phase of ~30 days. DNA extracts from these four bioreactors underwent amplicon sequencing (MiSeq, Illumina) using primers targeting the V3-V4 region of the 16S rRNA gene.