Water　disinfection　materials　should　ideally　be　broad-spectrum-active,　nonleachable,　and　noncontaminating　to　the　liquid　needing　sterilization.　Herein,　we　demonstrate　a　high-performance　capacitive　deionization　disinfection　((DID)　electrode　made　by　coating　an　activated　carbon　(AC)　electrode　with　cationic　nanohybrids　of　graphene　oxide-graft-quaternized　chitosan　(GO-QC).　Our　GO-QC/AC　(DID　electrode　can　achieve　at　least　99.9999%　killing　(i.e.,　6　log　reduction)　of　Escherichia　coil　in　water　flowing　continuously　through　the　(DID　cell.　Without　the　GO-QC　coating,　the　AC　electrode　alone　cannot　kill　the　bacteria　and　adsorbs　a　much　smaller　fraction　(＜82.8　+/-　1.8%)　of　E.　coil　from　the　same　biocontaminated　water.　Our　(DID　process　consists　of　alternating　cycles　of　water　disinfection　followed　by　electrode　regeneration,　each　a　few　minutes　duration,　so　that　this　water　disinfection　process　can　be　continuous　and　it　only　needs　a　small　electrode　voltage　(2　V).　With　a　typical　brackish　water　biocontamination　(with　10(4)　(FU　mL(-1)　bacteria),　the　GO-QC/AC　electrodes　can　kill　99.99%　of　the　E.　coil　in　water　for　5　h.　The　disinfecting　GO-QC　is　securely　attached　on　the　AC　electrode　surface,　so　that　it　is　noncontaminating　to　water,　unlike　many　other　chemicals　used　today.　The　GO-QC　nanohybrids　have　excellent　intrinsic　antimicrobial　properties　in　suspension　form.　Further,　the　GO　component　contributes　toward　the　needed　surface　conductivity　of　the　(DID　electrode.　This　(DID　process　offers　an　economical　method　toward　ultrafast,　contaminant-free,　and　continuous　killing　of　bacteria　in　biocontaminated　water.　The　proposed　strategy　introduces　a　green　in　situ　disinfectant　approach　for　water　purification.