Which life is supported in sterilized 100% pure water?
Of course many life forms can survive for some time in 100% water. A human for example can survive about 4 minutes in 100% water but I doubt this is what you are interested in! Although there is no commonly accepted definition of life, I think we can say that we all agree that any life form needs to reproduce or somehow grow. So I take your question as


  What life forms can reproduce or at least grow "potentially indefinitely" in 100% water?


Any life forms, to grow or reproduce needs matter to make its own constituents. As such, pure water won't provide with such nutrients and no life form can survive in the long run in 100% water.