Ion8 Slim water bottle review

Leakproof, you say? We'll be the judges of that

When I was a teenager, I got a plastic cap thing from a doorstep catalogue that promised to make my drinks cans leakproof. Being a trusting sort, I didn’t question this, slapped it on my open Lilt and put it in my school bag.

I don’t know if you’ve ever tried to surreptitiously peel apart the pages of your ruined Spanish textbook without attracting the teacher’s attention, or indeed whether you know the pain of trying to turn to page 26 when your textbook is now one 2cm thick, slightly wavy page. But I do know you’ll understand when I say I’ve had trust issues with the word ‘leakproof’ ever since.

These days, rather than textbooks, my bag is full of tech. Which means it’s even more important that my water bottle doesn’t spontaneously wet itself. Up to now I’ve ensured this by… not carrying a water bottle.

Yeah, not a great solution.

So when I was offered the ‘Ion8 Ultimate Leak Proof Water Bottle’ (quoting directly from the press release, can you tell) to try out, I decided to forgive, forget, and go for it. Here’s what I thought.

Ion8 Slim water bottle review

Ion8 do a few different water bottle styles: some for sports, some for kids, and so on. The Slim is a general-purpose medium-sized bottle that holds 500ml. It’s just about the right size to hold in one hand, then slip into my Knomo Grosvenor Place bag (which, granted, would probably hold a gallon without too much trouble, but water is heavy, so 500ml is fine). The Slim is the width of a drinks can, so it fits into the mesh pocket on your backpack, which is handy. Just don’t forget to take it out before you go through airport security (*cough* never done that *cough*).

The first thing I noticed is that it doesn’t reek of plastic the way some new bottles do. I gave it a rinse anyway, but the first sip of water from it didn’t taste like it had been marinated in polystyrene, and I appreciated that.

The bottle is made from non-toxic Tritan, which is a BPA-free, non-toxic plastic. It’s also resistant to odours and dishwasher safe, apparently — I couldn’t test this bit because I live in London and dishwashers are for millionaires. My bottle is the rather lovely Rose Quartz colour, but the Slim comes in 15 colours and designs INCLUDING UNICORNS so you’re not limited if you don’t fancy the same.


The bottle doesn’t come with instructions, and while you might not think you need them, it’s not entirely intuitive how you use it. The entire cap twists off normally, that bit was easy enough — and it has a nice wide neck that’ll easily fit ice cubes, and can also be retrofitted with a fruit infuser or a shake agitator if you so wish (sold separately, obvs).

However, drinking from the thing was a little less easy to figure out: it turns out you flip the curved bit down (that holds the lid on safely), then press the circular bit. It’s like a switch, and the lid flips off in a sudden motion that made me jump. Once you’re used to it, it’s the water bottle equivalent of an automatic umbrella, and quite satisfying. You can also do it one-fingered, which is nice.

The spout is well designed so you don’t get unpleasant glugging when speed-drinking (I will never, ever forget the man who went on Dragon’s Den with an anti-glug invention he’d spent ages on, and they said “just pour slower, duh”), and it’s a good size for getting a refreshing amount of liquid easily. There are measurements on the side as well so you can see how much you’ve drunk (also handy for shakes and suchlike), and it can handle hot or cold liquids.

There’s a little wrist strap in a contrasting colour, and a transparent lid with some jiggery-pokery on it that stops the bottle from leaking when closed. You put the lid on, then lock it in place with the flippy bit (which looks to me like it might be easy to snap accidentally, but they do sell replacements) and put it in your bag. I have tested this extensively (by which I mean literally whirling my bag around my head in circles, the things I do for you) and have not been able to get it to leak a drop.

However, if you forget the flippy bit, it may not hold (though I still haven’t been able to get it to leak this way) so it’s maybe not one for forgetful people.

Gadgette’s verdict

Overall, I like this bottle. It definitely is leakproof if you use it carefully, so my trust issues have been somewhat diminished, but you do have to be careful to lock it properly before you drop it in your bag. Being as anxious as I am, I check, double-check and triple-check this every time I use it, so no accidents here. Touch plastic.

The Ion8 Slim bottle is available for £9.99 from or, from March, Amazon UK. Happy hydrating.


Holly Brockwell
About Holly Brockwell 291 Articles
Tech addict Holly founded Gadgette in 2015, and won Woman of the Year for it. She's firmly #TeamAndroid, has ambitions to become a robot, and beat all other Hollies to her awesome Twitter handle.