Place the root samples in separate 100 or 150 ml glass beakers. Prepare 600 ml of a water-bleach solution by adding 100 ml household bleach (5% sodium hypochlorite or NaClO) to 500 ml distilled water. Add about 50 ml of water-bleach solution to each beaker containing a root sample.
Incubate roots in the water-bleach solution for 4 minutes, stirring with a metal spatula periodically. Rinse roots for 45 seconds or so in running tap water, then soak the roots in tap water for 15 minutes.