The water will last much longer IN the bottles.
Given what we have learned about the problem with plastic containers, I would consider non-ferrous metal containers for long-term storage of water. If you use plastic containers, I would replace the water every three months or so. That is my opinion, I have no authoritative reference to support it.

Glass I think would be best for a harmless inert container. I also have no authoritative reference.

First, i would open the bottles and pour the water INside, not on top. with that said, bottled water will be safe for up to a year. i would keep them in a cool location and avoid opening the top, until you are ready to use it all. bacteria can accumulate in warm water that’s open to the air.

Glass is definitely inert, but it can crack. Stainless steel is also inert (unless it is some modern crap stainless steel with insufficient chromium in which case it will rust way before it is supposed to) and not so brittle.

Based on personal experience I will say that if you store water in plastic for a significant period of time, it acquires a “plasticky” taste. Whether or not carcinogenic toxins are leaching out into the water from the plastic, I can’t be sure, but it sure tastes like it is.

If you are using plastic, make sure you keep it out of sunlight and heat which both can degrade plastic.

I hate everything about bottled water, but it sounds like you’d be better off buying a case of gallons of water and just stashing that. Then you don’t have to worry about bacteria because the bottles will be properly sealed.

And can I ask why 10 days?

As long as it doesn’t evaporate. As for storing it “in” plastic bottles I would say as long as the taste is agreeable.

Actually, your typo on/in leads me to remind us that tap water contains a lot of yucky, smelly chlorine and flouride – and it’s good to keep it open and on something, letting the container breathe – the chlorine will evaporate leaving you with tastier and healthier water. Remember to brush and floss, though. Just saying.

Emergency water supply preparation

@lilikoi 10 days so I have enough to speculate and make some money… of course I’m kidding. I don’t know, the number came to my head…

@BarnacleBill thanks great link, I saved it locally and printed it so I can have that reference anytime.

Thanks to all the others :)

When you put the water in the bottle add one teaspoon of bleach then seal tightly. It will be drinkable for years. If it has been stored for years and you have concerns you can boil it if you have an emergency cooking source. It will be flat tasting already so boiling will not make it worse.