To understand the appeal of a purifying water bottles, just think: What well-traveled dude doesn’t have a story about tangoing with local water or ice in a foreign country? Not every country has America’s reliably-clean drinking water flowing out of every faucet. And the danger from tap water is often much higher for visitors: Pathogens that the locals have acquired immunity to can ruin a traveler’s vacation in a hurry.
The usual way of going about things is to rely on bottled water. This works, but there are some obvious downsides: It’s inconvenient to carry around all the water you need, especially if you plan on a hike or other long adventure. And it can be hard to escape the feeling that all of that plastic is going to end up choking a sea turtle down the line.
The good news is that, these days, purifying water on the go is as simple as filling a water bottle. Where once the only options involved boiling water, dropping in chemical tablets, or relying on UV light, modern versions let you fill up from just about any water supply—from a river to the hotel’s sink. (Freshwater, that is—removing salt is much more complicated.) The purifier cleans the water inside the bottle as you sip, suck through a straw, or squeeze out a stream.
To find out which ones are worth packing, I tested a bunch during a recent international trip. It was good peace of mind to know any municipal water we had at the airport, hotels, beaches, or restaurants wasn’t going to tank the vacation, and the bottles made it virtually seamless.
Clean water 101: Filters vs. Purifiers
Before we dive into specific models, it’s helpful to know the difference between filtering water and purifying it. Side by side, water bottles that filter or purify look identical, function the same way, and, confusingly, some manufacturers offer both and use the terms interchangeably. So what’s the difference? It comes down to how small a containment the water bottle will yank out of your water.
Filters can catch bigger stuff, like silt, protozoan cysts, and bacteria like E. coli and salmonella. If you’re traveling domestically, this might be all the protection you need from municipal water or even clean lakes and streams. Purifiers take it a step further and can catch smaller contaminants like viruses (think: hepatitis A, rotavirus, and norovirus), which you might run into in less-developed parts of the world where human or animal fecal matter might make its way into the water supply. In short, a purifier can catch what a filter can’t, and that’s what we’re focusing on here.
So you should always just pack a purifier right? Maybe. Compared to filters, purifiers cost more, usually don’t clean as many gallons before they need a new cartridge, and often have a slower flow rate—anyone who waited for an old Brita pitcher to clean tap water knows how annoying slow flow can be . In some areas, it’s a level of protection that isn’t necessary. But if you’re traveling either in the backcountry or somewhere where guidebooks tell you not to drink the tap water, you want a purifier.
The Best Purifying Water Bottle: Grayl “UltraPress”
This unique purifier is almost fun. Instead of cleaning water as you drink, you fill the roughly 17-ounce removable outer sleeve with water, place the inner sleeve that has the cartridge on top. Then, using two hands, you press down on the inner sleeve, which forces all the water up through the cartridge. It’s a little like making a French press coffee. After a few seconds of pressing, the system bottoms out, and you have nearly 17 ounces of clean water in a normal-looking bottle that’s easy to carry, toss into a bag, or stash in a pocket.