recontamination

/ˌriːkənˌtæmɪˈneɪʃən/
noun
  1. The act or process of making something dirty, impure, or dangerous again after it has been cleaned or made safe.
    • The water treatment plant installed extra filters to prevent recontamination of the drinking supply.
    • To avoid recontamination, food handlers must wash their hands before touching any clean surfaces.
    • After sterilizing the surgical tools, the doctor worried about recontamination from the dusty air.