Spending most of my time in the highlands, I don't tend to worry much about treating or filtering water. With few sheep and fewer people around to pollute them, the high burns usually run clean, and I've never had an upset. But even here there are times and places to check that relaxed attitude. I would think twice before drinking unfiltered water in busy locales such as Torridon or the core Cairngorms, and treat with suspicion any source close to the popular path that you'll find on every Munro. Head to the Lakes or Snowdonia and the pressure of livestock and people crammed into a small area would make routine filtering a sound precaution.

Chemical treatments taste foul, while bigger filters aimed at base camp can be a bit heavy and fiddly on a day out. For my needs (and I'd say that probably goes for most walkers and climbers in the UK) something small, light-ish and simple is best, a bottle or a straw-based filter that's good for just drinking on the go.

I've been looking at two options from Lifestraw's Peak Series range that very much tick this box: the Collapsible Squeeze Bottle and the Personal Water Filter Straw. The larger Gravity filter from that range would be more of a basecamp option - a review for another time perhaps.

Robust, easy to use, and reasonably light, both the Filter Straw and the Squeeze Bottle seem pretty effective. At least, I've not yet had any regrettable incidents.

Collapsible Squeeze Bottle water filter system - £44.95 - £49.95

Squeezy bottles are my filter of choice on the hills, since they pack down small, do the job with minimal faff when you're on the go, and give you some capacity to take the water with you rather than drinking only at source. This is a particularly good one - versatile, and with a robust feel.

Capacity

Two sizes are available, 1L and 650ml. I often find myself carrying this sort of filter as a backup to my main bottle (filled from a guaranteed safe source), and for days like that the 650ml version seems ideal. If you're using this as your only water carrier then I guess 1L is the one to go for.

Weight

According to the product blurb the 650ml weighs 102g, while the 1L bottle is 110g. Once the filter is wet (it's supposed to be kept thus) you can realistically add around 15g to that. It's not the lightest thing in the world, but for the job it does, and the general feeling of toughness, the weight is more than fair.

Versatile?

Yes! LifeStraw have cleverly set it up so that the filter part of the nozzle is removable, allowing you to leave it at home and use the bottle as, simply, a bottle. You can also screw the whole nozzle/filter assembly off and suck straight through, drinking straw-style direct from a shallow source. In addition the filter can also be connected to other LifeStraw Peak Series gubbins such as the Gravity. This flexibility is great.

How it works and what it filters

Filtering out 99.999999% of bacteria (that's a lot of decimals as well as a lot of bugs), 99.999% of parasites, and 99.999% of microplastics, the Squeeze Bottle has you covered for many potential waterborne nasties. No mention is made of viruses or chemical pollutants, but perhaps those are extreme applications for something this simple and compact; if that sort of thing was a concern on a fun day out in the UK hills then I might be thinking about my life choices.

If the water isn't running clear, then the filter should be able to take out silt, sand, and cloudiness greater than 0.2 micron. Its effective temperature range of 0C - 60C should see you right in most situations, though perhaps my winter use to date has taken it close to the lower limit.

This membrane microfiltre lasts up to 2000L, which is a lot of hillwalking or backpacking and just a couple of pence per litre. It meets US EPA and NSF P231 standards for the removal of bacteria and parasites.

As usual with this sort of thing, you've got to squeeze and/or suck reasonably hard, though the stated flow rate of up to 3L per minute does sound pretty good.

Maintenance

This isn't something to just store and forget about, it's a little bit particular since it wants to avoid drying out in order to maintain the properties of the filter, and to prevent the growth of mould and suchlike. If it's being stored for more than one month with no use, LifeStraw recommend filling it with a saline solution, while for storage over three months they say to clean it out with a diluted bleach solution (!) too. I doubt I will always remember (or be arsed) to do all this, which may have a bearing on the filter's effective longevity.

The filter also needs to be flushed out regularly, to keep unclogged: a 'backwash syringe' is included to do the job.

Personal Water Filter Straw - £34.95

An update on the brand's popular filter straw, this is the ultimate drink-on-the-go option, letting you access shallower puddles and trickles than you might be able to fill a bottle from.

While the Squeeze Bottle's filter can also be used as a straw, giving you the best of both worlds, the Filter Straw is clearly more limited since you're drinking at source and can't carry the water with you. Yes it's possible to dock it with a standard disposable drinks bottle, which is a nice touch, but that does seem a bit of an elaborate work-around for outdoors uses.

However the Straw has minimalism in its favour, and may be a good option for runners or ultralight walkers confident there'll be plenty of water sources on their route. It's also a tenner cheaper for a filter that's equally effective, and which will go on working for double the amount of uses before needing to be retired.

Weight

At just 65g (dry weight - it's a bit more once the filter is wet) this is the lightweight option of the two. Not too bulky, it also feels nice and robust.

How it works and what it filters

You get the same filtering performance as with the Squeeze Bottle - 99.999999% of bacteria, 99.999% of parasites, and 99.999% of microplastics - and with a pore size of 0.2 micron it'll cope with silt and sediment. Due perhaps to its longer length, this version of the filter will do you for twice twice the amount of water, a pretty impressive 4000L. You have to suck pretty hard, and you'll know the product has reached the end of its working life when you can no longer sip through it.

Maintenance

Again, it's recommended that the filter be protected from drying out. To keep the pores clear of debris, simply blow back through.