I love frozen bottled water. Whenever one of the drink coolers malfunctions or is set too low and freezes a few, I always buy a frozen one.

As for your plan to sell them on the street, most places have permit requirements for street vendors, so if you decide to try this look into how to get one of those permits.

Off topic:
http://answers.yahoo.com/question/index?qid=20100718144953AAKPYe1

I have seen precisely this done in Denver.

Whoa. Scary comments machine.

Anyway: by what proportion does your average mineral water expand when frozen? Is it less than the amount of space available in the bottle for it to expand into? If not, you'd have to open the bottles to let some more water out, which would wreck the liability thing, alas.

I expect to be corrected if I'm wrong, but the plan is to freeze "ordinary" bottled water -- which is usually just commercially filtered water, whether from a reservoir (i.e. tap water) or spring water -- not mineral water. Mineral water generally comes in glass bottles, making it a bad idea to freeze, but bottled water usually is in a plastic bottle which has at least a little give.

What would be a really cool gimmick, although seriously impractical, would be to supercool the bottles and freeze the water for the customer while he watches after he has bought it.

Sounds like a great idea. The only problem would be morons out there saying that by freezing the water in the bottle it causes carcinogens to leave the plastic. Or something like that. I know I've heard organic freaks out there saying something about that.

1. This reminds me of the old story about coca-cola's idea that vending machines will charge more on hot days (by measuring the temperature).
2. Where I live (Israel) it gets pretty hot as well, and there are many small shops that sell cold drinks. Doesn't it happen in London as well?

I'm surprised that nobody has mentioned this yet, but what about the heat generated by the freezing of the bottles?

I'll skip the lecture on thermodynamics, which you probably already understand. You don't want hundreds of mini-freezers running on the streets of London during a heat wave. They would just be pumping even more heat into the air. And if you freeze mass quantities of water at an outside location, you'd have an enormous heat output there, plus the additonal heat generated by the vehicles transporting the frozen water to the street vendors, and still more local heat output to try to keep the bottles from melting during the day.

The heat generated by the freezing of the water, which is emitted from the freezer in the form of hot air, would be infinitesimal compared to the heat pouring down all over the entire city from the Sun. I mean, even on a normal hot day in London there are huge numbers of vehicles, generators and freezers running. The Sun overrules them all, though.

But more heat will make more people want frozen water! I say you run a heater alongside your freezer.

Actually, I have a vague memory of freezing bottles of water to take with me on holiday... it's nice in some ways, but a little annoying when you actually want to drink the water.

Actually, in an enclosed space like the underground, heat from enough freezers could build up. The NYC subway system has this problem, where the cars are air-conditioned, and their AC units dump all the heat outside, into the station. So you're okay in the cars, but when you're waiting for a train on the platform, it's a sauna.

Vendors do this in China everywhere. Sometimes they'll have both frozen and unfrozen bottles and charge more for the frozen ones.