Home Gear A closer look at water filters for adventure
Feature type Spotlight
Read time 15 min
Published Aug 31, 2022
Author Hannah Mitchell
For many of us in developed nations, these days it can be easy to take for granted access to clean water at our fingertips. But getting safe drinking water to our taps is a hugely complicated process; from the engineering of the water systems – the network of pipes and pumps below our feet and behind our walls, the water treatment process, urban infrastructure and of course, the water source itself, right down to how and where it is stored.
For those of us then who actively choose to spend time in places where our water sources are not treated – be that in the backcountry or abroad where those same, meticulous systems aren’t always in place – accessing safe drinking water can present a major challenge and the repercussions of getting it wrong are no joke.
While reliable filtration on the move can greatly reduce the chances of waterborne illness, today the environmental impacts of filtering our own water on the move are equally valid. The less we can rely on single use plastics to provide us with safe drinking water, the better.
Below, Hannah Mitchell takes a closer look at the history and development of water filtration systems and the innovators within the outdoor industry making a mark today.
While the pollutants themselves have evolved alongside industrial advances and population growth over time, filtering water is a practice that can be traced back over 2500 years. The first ever example of the water filter is thought to have existed as far back as 500 BC, the creation of the famous Greek physician Hippocrates. This early incarnation utilised a simple cloth bag to sieve impurities from the water drawn from aqueducts, which had been first boiled in order to make it somewhat more palatable, and less fragrant.
Moving forwards, the evolution of water filtration for the home began to incorporate more sophisticated methods and materials as our knowledge of bacteria, parasites and other unpleasant entities that can lurk in liquids grew. The Doulton Filter was designed in Britain during 1847 as an answer to the increase of raw sewage in water sources such as the Thames which were causing widespread cases of Typhoid and Cholera. The invention by Henry and John Doulton of the English fine china brand, comprised a porous ceramic bowl which was placed above another bowl, and the dirty water poured into it. Larger particles could not pass through the pores of the first bowl, so cleaner water could be collected from the bowl underneath.
Microscopically, viruses are a lot smaller than bacteria, and this makes them pretty tricky to filter out. For reference, a human hair measures approximately 30 microns, bacteria 0.3-5 microns, and viruses between 0.005 and 0.3 microns. Previously, common methods of removing viruses from water were boiling, UV light or by adding chemicals. Common chemical purifiers include chlorine that is often present in our tap water, or Iodine which is common in germicidal water tablets. Developments including the use of chlorine dioxide in tablets, drops and powders mean that this form of purification is highly effective in removing microorganisms when water is of questionable quality. But whilst they are lightweight and easy to carry when camping, chemical tablets won’t remove physical particles like dirt, and ironically, that dirt can actually impede the effectiveness of chemicals and UV light.
The most common and effective method of filtration and purification involves passing unsavoury water through a porous membrane of some sort, which catches the waterborne baddies
Now, it’s important at this stage to differentiate between a filter and a purifier. The terms are sometimes used interchangeably, but if you’re in the market for either, it’s not only important to ascertain which you need based on its intended use – it could be critical to your health too.
The difference lies in the level of protection the system provides against harmful substances and microorganisms that might have entered the water. Filters such as Doulton’s, and later counter-top incarnations that we might associate nowadays with brand names like Brita, will usually fall under the category of a filter. This means that generally speaking, their membranes will improve turbidity (the clarity or lackthereof caused by particles like mud and silt), remove bacteria, parasites and protozoa, but not viruses. Purifiers on the other hand, will improve turbidity, remove bacteria, parasites and protozoa, and viruses too.
Physical water filters and purifiers operate in largely the same manner in terms of form and how they remove those aforementioned nasties, but with a few variables depending on their purpose. The most common and effective method of filtration and purification involves passing unsavoury water through a porous membrane of some sort, which catches the waterborne baddies. Put simply, a purifier will work in the same way, but utilises a finer internal membrane system than that of a filter, so as to capture those much smaller, pesky viral particles. It’s sort of like using a sieve, and the smaller the holes in that sieve, the smaller the particle or organism it will catch. As for function, some use a pump mechanism, others a gravity feed to draw water through the system.
Nowadays, home filtration is commonplace, but what about when you’re moving fast and light? You can’t take the kitchen sink with you on a long-distance run, ride or hike.
Lucky for us, water filters and purifiers have come a long way since the days of Doulton, and there are many options available to suit your activity choice that won’t weigh you down. Larger capacity, pump or gravity-fed systems are a great option for expeditions where they can be left in situ at a basecamp, whilst portable options range from systems that syphon into your water bottle or cooking pot to versions that you simply fill up and drink from directly – and some that do both.
In the ‘90s, outdoor gear manufacturer MSR (Mountain Safety Research) began to explore how they could develop a better water filter for backpackers and outdoor enthusiasts. Aware of the effectiveness of ceramic filters but inhibited by the cost, the heads at MSR began to explore the extrusion of ceramics, a process that greatly reduced production costs. Several years later, the MiniWorks ceramic filter was born, and in 1998, was recognised by the American Ceramics Society as one of the most important ceramics innovations of the century. Since then, the brand has continued to forge ahead with developments in filtration with its own team of water scientists and microbiologists operating out of their lab in Seattle, pioneering systems for use not only by intrepid explorers, but the military and philanthropic organisations in aid efforts too.
Contemporary filtration and purification systems for outdoor activities now commonly use hollow-fibre membrane technology because of its lightness, efficiency and comparatively fast flow rate. Hollow-fibre cartridges are made up of hundreds of tiny, closed loop tubes that are open towards the incoming water. The straw-like tubes which are filled with microscopic pores are bundled together to form a matrix. As water passes through, either by pump, suction or gravity, particles are trapped inside and clean water passes through the pores, making it safe for you to rehydrate.
In many trekking, camping or expedition scenarios, a filter is a perfectly acceptable means of making your drinking water safe. Whilst purifiers might be the gold standard in sanitising water from backcountry sources, they aren’t always entirely necessary. Parasites including protozoa and bacteria are transferred inter-species via faecal matter in water, viruses are a little more picky though, and will usually only jump between members of the same species. This means that if human activity levels are high around your water source, there is a greater threat from viruses and you’ll be wanting to use a purifier. If human activity in the area is relatively low, there’s a good chance you’ll only need a filter.
‘When you’re backpacking in an area where there’s a crowded campsite and there might be human waste present, or if you’re abroad in an area where sewage treatment isn’t that well established, you need that virus protection,’ explains Kevin Weitz, who is the Water Lab Manager for MSR.
Originally developed for military use, MSR’s Guardian Purifier has a plunger or pump mechanism that is connected to a flexible tube which syphons water from the source, directing it to the hollow-fibre filter cartridge and then into your bottle. Weighing in at 0.49kg and with a flow rate of 2.5l per minute, the Guardian is now a firm favourite amongst global travellers and backcountry campers for its efficacy in removing everything except chemicals and toxins and eliminating the need for single-use plastic water bottles.
But there’s more to MSR’s Guardian than meets the eye, it’s one of the very few filtration systems publicly available that meets U.S military standards – able to provide deployed personnel with the capability to produce sustainable quantities of safe drinking water in any environment. MSR is able to achieve this certification because of their in-house microbiological testing and ongoing research at their factory in Seattle, U.S.A.
That crystal-clear stream could be harbouring a myriad of microorganisms ready to give you the bellyache of your life, or worse
‘The Guardian technology is unique because it’s one of the only water filters out there that meets the P248 standard,’ explains Weitz. ‘P248 is a rigorous 10-day test that uses both clear water and water so contaminated it’s called worst-case water.
‘It is very important to have a biohazard level 2 lab because we can grow bacteria and microbes that users might encounter in the backcountry that would make you very sick,’ he continues. ‘Being able to grow our own microbes on site is a huge advantage to our product development process.’
For most of us, safe water at home is something we give very little thought to as we freely top up our glasses. In the wild however, it requires a little more consideration. Behind the idyllic aesthetics of that crystal-clear stream could be a myriad of microorganisms ready to give you the bellyache of your life, or something far worse.
On expedition, a quality filter or purifier eliminates the limits of clean water access as well as the need for bottled water, saving you money, and lessening our environmental impact too. To do so is of course is a privilege in itself, and the brains behind MSR’s systems are developing solutions not only for their adventurous customer base, but also for communities around the globe for whom safe drinking water is a precious commodity.
So, whilst a water filter or purifier might not be the sexiest, most flashy item in your pack, with the ability to take you beyond the limits bound by clean water accessibility and to potentially save lives, while saving the planet as it goes, it could be the one to change the game completely.
Contaminants can mean a whole range of different things, from the not-so-dangerous to the straight-up life threatening. The key thing to remember is that many of these contaminants are undetectable to the human eye but may still have the ability to cause serious damage to our health.
If you’ve ever suffered sickness from unclean water you’ll know what we’re dealing with here. Generally speaking, water contaminants can be categorised by the following:
These microscopic nasties are the primary focus of treatment devices because of the immediate risk they pose to your health. This might include bacteria such as E-coli or Salmonella, protozoa like Giardia and Cryptosporidium, and viruses like Hepatitis A or Norovirus.
Sediment gives water a dirty appearance, this could be sand, silt, mud or glacial flour that enters the water naturally by the erosion of river beds, banks or rocks. Whilst generally harmless, it’s not very nice to ingest!
These are what gives water that tea colour, decaying plants and leaves leach organic matter into backcountry sources. They’re not harmful in small quantities, but they do impart odours and a bitter taste that even milk and two and sugars won’t sort out.
Pollution of water sources with pesticides, herbicides or inorganic chemicals from both industrial activity and natural erosion can cause health risks, usually from long-term, repeated exposure.
The result of natural erosion or seawater contamination, the primary problem with salts is that they simply make water taste bad, and high concentrations can dehydrate you.
Metals can enter water sources through industrial contamination or natural erosion and cause poisoning. The metals most commonly associated with poisoning of humans through water sources are lead and mercury.
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