Aqaurium Rock Help !!!!?

  i have river rocks that i would like to use in my turtle tank so he can have extra room out of the water, what do i have to do to make them "safe" for the tank? what do i scrub them with or boil or bake or what ????? Help Please! Thanks!!!
some say soak i parts bleach 10 parts water but i go with boil
I get river rocks for my turtles and fish tanks and all I do is wash them off in the river before I bring them home. Fish and other live animals live and drink from rivers.
Boil