In this study, the possibility of modifying polyamide 6 (PA6) nanofibrous membranes with three organic biocides Bronopol, WSCP and TCMTB and their effect on the properties of the polymer solution, fiber morphology, water permeability and bacterial removal efficiency was investigated. The membranes were prepared by electrospinning from a PA6 solution in a formic acid/acetic acid mixture and each biocide was added to the solution separately at different concentrations. The viscosity, electrical conductivity and surface tension of the solutions were measured and the fiber morphology and additive distribution were evaluated by FE-SEM and EDX. Also, the removal efficiency of Staphylococcus aureus bacteria and the leaching of biocides were investigated. The results showed that the addition of biocides increased the viscosity of the solution, and its maximum was observed at 0.05% omf; while WSCP significantly increased the electrical conductivity and the surface tension did not change significantly. The fiber diameter remained almost constant up to 5% omf, but increased at 10 and 20% omf for Bronopol and WSCP. The clean water permeability of the membranes was high and no significant differences were observed between the samples. Despite the modification of the membranes, increasing the biocide concentration did not necessarily lead to increased bacterial removal. These results indicate that modification of PA6 with organic biocides is feasible for water filtration applications, but optimization of the membrane structure is necessary to improve bacterial removal.