[prettyStandard]

I've always heard that if you want to sanitize water for bacteria you can put the water in the sun for half an hour and that will kill all the bacteria. I've also wondered what the growth rate of bacteria would be in water without any food in it. I guess to answer your question on if they're worth it or not is when do you primarily use your water bottle? If you're out hiking in the sun or something probably no If you're indoors mostly where the sun isn't accessible then maybe yeah. I don't think they're worth it I would just wash out the bottle on occasion.

[ravin_derk]

Even in Indoor environment you can always boil the water as an option. I seriously doubt if UV is required to be fitted in a bottle untill and unless we are talking about seriously dirty water.