Do filter water bottles for hiking really work? We tried one out on this dodgy stream water!

Water is a pretty important part of our daily lives, and even more so when enjoying the outdoors. From summer heat to winter hill-climbing exertions, it’s vital to replace that lost water fast to keep spirits (and general enjoyment) up. While that’s an easy task at work, home and up the gym, not all outdoor locations have immediately drinkable water on tap, which is where the LifeSaver Liberty comes in. 

The theory behind the device is that it’ll filter water that isn’t drinkable, removing 99.999% of viruses, 99.9999% of bacteria, and a mere 99.99% of cysts. Holding 400ml of filthy ditchwater that can immediately be consumed as if straight from a spring, it sounds like a perfect companion for many an outdoor adventure. We took it out on a day’s hiking to see how it holds up in reality, and is worthy of a place amongst our best water purifier and best water bottles for hiking guides. 

The first thing you need to know about using the LifeSaver Liberty outdoors is that it needs priming before you leave the house. This isn’t a big task, but an essential one. You basically fill the reservoir, empty, then refill and pump water through twice, leaving you with a damp but operational water filter system. The instructions also make clear that once primed, the membranes must be kept ‘hydrated’, by storing ‘at least 1cm’ of water in the bottle at all times – a potentially slightly faffy process, as well as something of a storage challenge.  

Perhaps it’s a case of tester incompetence, but as a standalone water bottle the LifeSaver Liberty can be quite demanding. The reasons for this are both good and bad, based around the built-in pump, which is used to force the sketchy water through the filter and then out the top spout as clean drinking water. The good news is that you don’t need to suck to perform this feat, the bad is that it requires a careful hand to get the valve and internal pressure set for easy drinking. A fountain of filtered water rewards the less competent, and while it’s easier than you’d expect to pump and drink at the same time, it does need both hands and ideally to be stationary – drinking on the go is a challenge, even at walking pace.

Where the LifeSaver Liberty really shines is as a filter for a larger group, especially with the additional scavenger tube, a highly practical addition that means you don’t actually need to climb into the river or muddy lake to get water – a detail that seems unimportant until you’re actually trying to fill a bottle from a river without donning waders. With the scavenger tube dangling down into a babbling brook (of slightly suspicious-smelling water), pumping away soon slurps up enough to fill the 400ml capacity, and allows one person to sip from the water-fountain style top nozzle.

However, even in a small group, the clamour to ‘have a go too’ soon meant that attaching a Nalgene bottle to the top thread and pumping the water directly into it was the only sensible solution. Each pump produces a gratifying slosh of filtered water into the Nalgene, which can then be decanted easily into whatever variety of bottles you have to hand, or used directly. We were easily able to refill a range of bottles within a few minutes, from a water source that only the very brave would have drunk unfiltered.

The scavenger hose is particularly helpful when filling a second bottle, as the only limit to the volume of water you can filter with it connected is the life of the filter - 2,000 litres. The water source end of the pipe has a removable screen arrangement to keep big debris from blocking the pipe, and a foam float that’s presumably meant to keep the mouth of the pipe off the bottom. We found the float unnecessary in the streams we tested the LifeSaver Liberty in, but it might be handy in shallow, still ponds and the like, although the pipe and filter are fairly buoyant anyway.

Overall, the LifeSaver Liberty proved impressive in the field, quickly and efficiently filtering water from dicey sources for a group. As a standalone bottle the system does work, but it is a bit of a compromise, much better used as a method to refill normal bottles. There is a weight penalty for the latter, of 425 grams dry, which is quite an overhead in most UK situations. However, as a tool for treating tap water in the many places across the globe where direct drinking isn’t recommended, and for hiking in areas such as Giardia-riven New Zealand, the LifeSaver Liberty is an essential tool in the box.