There is a commercial product, the Puralytics solar water purifier made with a msh of titanium dioxide. Depending on the intensity of the sunlight, it takes 2 to 4 hours for the blue color dye to disappear and indicate that the water is safe to drink.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.