Subject: Does liquid bleach has to be diluted to be effective as a virus killer?

I had a person telling me that if liquid bleach was not diluted into water 
before using it, it would not be effective to kill viruses & bacteria. I 
believe that even if I use the liquid bleach undiluted, it will still be 
effective as a virus killer.
I guess we dilute it to be more environmentally safe as a small quantity can 
work as well as a large quantity, sometimes even better.
Thanks for your answers!

Re: Does liquid bleach has to be diluted to be effective as a virus killer?