Experiments to evaluate the photocatalytic activity of supported TiO2 to potabilize water in common plastic PET bottles tinder solar irradiation were performed. Commercial titanium dioxide (Degussa P-25) was applied to different cheap materials-glass rings, glass rods and porcelain beads-by dip coating, or directly to the plastic wall of the bottles. The adherence and stability of TiO2 on the supports and the photocatalYtic acti. vity in bottles under solar irradiation was evaluated using model compounds as 4-chlorophenol and 2,4-dichlorophenoxyacetic acid. Rings were found to be the best glass supports, but PET bottles were superior,for this specific application, as no fragile fillings are used, and the materials can be easily fabricated oil site.