We recently reviewed my go-to gravity-based water filter system, the Katadyn Gravity BeFree system. However, more brands have joined the game. Read on for reviews of two additional gravity-based systems, both of which have their pros and cons.
LifeStraw Flex with gravity bag:
Pair the confidence you already have in LifeStraw with the convenience of filtering a gallon of water at a time. You get next-level protection against heavy metals including lead as well as bacteria, parasites, microplastics, and organic chemical matter like pesticides, and herbicides, all in a ultralight system. The whole thing only weighs 6 ounces, and can filter one liter every two minutes. As always with LifeStraw, when you buy a product, you give a product to one school child (one year of clean water).
It works in the same manner as other gravity-based systems: just fill the bag, hang, add the filter, and allow the water to drip through the filter and into your water vessel whenever you need it. Alternatively, you can use the LifeStraw filter individually like you would any LifeStraw, which is a nice bonus of versatility. Pick up the system on LifeStraw for $54, a great value, or look for it on Amazon for the same price point if you prefer.
The GravityWorks system is similar to that of the LifeStraw and Katadyn varieties, but it involves two bladders instead of one. This can be a pro or a con: on one hand, the system is slightly heavier and bulkier to pack, but on the other, you have a dedicated clean-water bladder to use in a variety of ways, storing clean water and carrying it to your next backpacking location, for instance.
You can choose between a 2 liter and 4 liter kit (I like the 2 liter). Just fill the ‘dirty water’ bladder with lake, stream, or iffy hotel water, then attach the included hose and filter system between it and the dedicated clean water bladder. Hang the dirty water bladder higher (hence the use of gravity), and wait for your water to fill the bladder. The disadvantage to this system is that you have to wait for the clean water bladder to completely fill, which can take a matter of about 20 minutes. With the other systems, you can have water on demand, though you might have to squeeze the bag a bit if you’re impatient.
With the GravityWorks system, you get extra parts, including a universal bottle adapter. Pick up the Platypus GravityWorks on their official site for $99 for the 2 liter size, or look on Amazon.
Remember to pack at least one individual filter system as well, such as the individual LifeStraw or the Grayl GEOPress.