Although most of the time we're lucky enough to have clean water easily to hand, it's not always that easy in the outdoors. Even if you invest in the best hiking water bottle and make sure it's filled up before you leave home, long days and hot weather can mean you end up water-less halfway through a hike. And that's to say nothing of wild camping adventures and multi-day expeditions.
In cases where a drinking water tap is elusive, you're left you with the options of either going thirsty, or drinking from local water sources. These can range from fast-flowing streams that are probably fine, through to still water and rivers that probably aren't. While there are a few ways to purify water in the wild, perhaps the easiest is to head out armed with one of the best water purifiers. These are designed to make even the most unpalatable pondwater not only safe to drink, but improve the taste so it's almost like you're just drinking from your kitchen tap.
A quick note before we start. This guide is dedicated to the kind of water purifiers you'd take out and about with you. If you're looking for the kind of thing you keep in your fridge and use to remove impurities from your local tap water, you should head to our best water filter jug guide instead.
What's the difference between a water purifier and a water filter?
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A water filter will be a common sight around the home; it'll take standard tap water and clear out unpleasant smells, often using a replaceable filter containing activated carbon. Some are connected inline with home taps to perform the same job. However, they're not designed to tackle water that isn't safe to drink in the first place – that's where the water purifier comes in. A water purifier will actually clean dirty water, removing nasties such as viruses, protozoa, bacteria and cysts, none of which you really want to be drinking. Many of the best water purifiers will incorporate a carbon water filter too, which will remove any non-dangerous smell and flavour from the purified water.
The best water purifiers to buy now
The Lifesaver Liberty is an impressive bit of kit, offering high-quality water filtration as well as a carbon filter to make even the foulest liquid into sweet-tasting nectar. The ingenious system is essentially a pump with a 400ml capacity, which you can fill from whatever source, then use the pump to force the dirty water through the filtration membranes, creating a spout of clean water. The clever bit comes in with the built-in thread, which fits a range of wide-mouth water bottles, and the 'scavenger' hose, which dangles down into otherwise inaccessible water. The result is a simple and compact water pump, that'll fill as many bottles as you need for your group from whatever water you come across. Simples. The replaceable filter is good for 2,000 litres, while the carbon insert manages 100 litres before needing replacement. Head to our Lifesaver Liberty review to see how we got on when we tested one out.
The LARQ Bottle PureVis is the ideal solution for anyone who tries to avoid single-use plastic water bottles for daily hydration, but can't help noticing that sustainable, reusable water bottles tend to go a bit stale and whiffy after a few months of regular use, even if you scrub them regularly. Hailed as 'the world's first self-cleaning bottle and water purification system', the PureVis uses UV-C light – via an LED in the lid – to destroy 99.99 per cent of odour-causing germs, bacteria, viruses, and other harmful bio-contaminants, which makes it perfect not only for on-the-go water purification, but also for keeping the bottle itself delightfully fresh.
You can purify your water by pressing down on the lid and simply waiting 60 seconds for the UV-C light to do its thing, while its self-cleaning mode activates every two hours, so even if you bring your bottle home from the gym and forget about it for a few days, it'll still be fresh when you remember about it, as long as the battery's charged. Yes, it needs charging (which takes four to five hours), but a full charge will last you a month.
There's no escaping the fact that the LARQ Bottle PureVis is a lot more expensive than a reusable bottle, but its insulated version will keep things cold for 24 hours, which is a definite bonus, and the thought of being freed from regular scrubbing is an absolute plus, and it's thoroughly easy to use, too.
The LifeStraw Go wears its heart on its sleeve. A standard litre-size BPA-free drinking bottle, the cap has a socket to host one of LifeStraw's filters. The result is clean water – all you have to do is fill with appropriate ditchwater, and then suck it through the filter. The microfilter lasts up to 1,000 gallons (4,000 L) and the activated carbon filter lasts up to 26 gallons (100 L) of water – enough for the average trip, by a considerable margin. The bottle can be used without the filter too, so is handy round the house, gym or office, etc. The company has a strong ethical stance too, giving one child one year of safe water per purchase.
The Salomon SOFT FLASK XA has a plan, and it's a pretty good one. By pairing a super-lightweight, flexible flask with a water purifying filter cap, the outdoor brand has created arguably one of the best ultra-trail running water devices on the market. Filtering out bacteria and protozoa from approximately 1000 liters of water, the high flow valve lets you hydrate on the move, top up from whatever water sources you stumble across, and shrinks as you drink. This is important to limit water bounce, as well as help stuff the flask back into your running vest or belt.
If you're off on expedition to a hostile environment, where you know clean water will be in short supply, then you want the MSR Guardian Gravity Purifier in your duffle bag. It's designed to military specifications, so rugged as they come, and it's simple to use, thanks to the gravity element. Just hang it up, fill with filthy water, and let it percolate through the NSF protocol P248 military testing standard filter and two-stage purifier with activated carbon. You'll get up to a litre in 2 minutes with the right setup, an impressive flow rate. While it's not a portable system once setup, it packs down small for travel.
We're not sure you'd want to rely on the Lucy Smart Cap if you're fending for yourself in the wild, however if you want an easy way to give your everyday drinking water a once-over, with the added benefit of a system to keep you hydrated, this one's well worth checking out. The Lucy Smart Cap has a built-in UV-C LED; put it on one of Waterdrop's water bottles, press the button and most unwanted potential germs will be dealt with in around 90 seconds. Simple and effective.
The Lucy Smart Cap records your water consumption, too, and paired with the Waterdrop Hydration app, the whole setup becomes a smart drinking assistant that monitors your hydration and reminds you when it's time to take another sip. Find out more about our experience with the Lucy Smart Cap here.
The Sawyer Mini Filter is justifiably popular thanks to its long life (100,000 gallons), tiny size (65 grams) and considerable flexibility. It'll work as a straw, to drink dirty water direct, an attachment to standard threaded bottles, or inline in a bladder-style hydration system. The long life is down to the fact that the filter can be cleaned (backwashed) with the included syringe, which will restore up to 98.5% of the filter’s flow rate. For such a tiny palm-sized device, that's an impressive list of accomplishments. As Sawyer says: 'A lifetime of water at hand'. Indeed.
