Why not household bleach? Extremely effective against bacteria imbedded in plastic. If it's used sensibly, it's perfectly safe for PET, vinyl, silicon, etc.
1/2 cup of household bleach per 5 gallons. Add equal parts of white vinegar (when the water has diluted the bleach) to increase the killing power of the chlorine (it lowers the pH, similar to a swimming pool environment.) Let it soak for a few hours and it's bacteria free. Simple, cheap, effective.