Are UV water bottles worth it?

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.

>for sailing boats with water makers when the UV module fails

UV add-ins for water makers are a peace-of-mind option for boats with very large tanks that have opportunity for fouling; they are by no means common in the water-maker loop except in the very high-end; the high pressure membrane filters do the job just fine.

plus side : most sailing offers all the UV you could ask for. Grab a bucket and hit the deck, no need for future-bottles.

It really depends what you're trying to solve for. UV light will kill bacteria but sometimes the dead bacteria can be more toxic than the live ones. Same goes with boiling. Is it better than untreated water? Yes, of course it is but is that what we're comparing against?

You need water in an emergency and your only option is an non potable source therefore I have a UV light bottle for just such an emergency. If this is your use case I'd say get life straws. They'll work better and you don't have to worry about toxicity from bacterial death. Wherever you're going that you have the option of carrying a UV light source for water treatment you'll have better options you can carry to treat water.

In my opinion these bottles are sold to be trendy and have that's shown by the marketing. You'd never want to rely on this for treating non potable water. It seems more about people too lazy to wash their reusable water bottle every few days and thus killing off the bacteria that starts to grow inside that gets transferred from your mouth. Gross thought, but just wash the bottle.

Thanks for the replies - had a look and general feedback for the top two brands seems to be that the lid that holds the UV light breaks after a few months. They seem to be as effective as water purification tablets but right now the price is a bit steep for what you get.