Types of Outdoor Water Filter
Safe water is crucial to backcountry hikers. Unsafe water can make you sick with a range of unpleasant and potentially life-threatening diseases.
Choose a backpacking filter that prioritizes your safety while keeping maintenance costs low. Reliable models feature a backflush system for use with turbid water and are resilient to freezing temperatures.
Pump Filters
A pump filter is the bulkiest, but also the most reliable backpacking water treatment option. Its components are made to be durable in the wilderness, and most offer a great deal of functionality compared to simpler chemical purifiers or UV systems.
A backpacking pump filter consists of a receiver tank and a separate filtrate tank. Water is pulled from a source through the pump line into the receive tank, where it falls down through a ceramic filter. Each pore in the filter is like a little prick, with lots of rough edges to grab onto water particles. Over time, these rough surfaces wear down a bit, allowing a few tiny water particles through, but most contaminants are retained in the filter.
Once the filter is filled, water is pumped through into the filtrate tank. The water passes through a 0.1 micron pre-filter, which removes large contaminants and improves the overall quality of the water. Then, the main filtration process takes place through a proven 0.01 micron filter that can remove viruses, bacteria, protozoa and heavy metals from the water.
The MSR Guardian is ten times more expensive than most of the bottle filters here, but it’s worth the investment for those who spend a lot of time in the backcountry. Its self-cleaning mechanism allows it to withstand far more backcountry use than other pumps, and its large filtration capacity makes it an excellent choice for groups of hikers.
Gravity Filters
Rather than pumping water, gravity filters use the force of gravity to draw it from a dirty bag, through a filter and into a clean reservoir. This makes them simple to use – just fill a bag, hang it, and wait. They also don’t require electricity, which makes them ideal for wilderness trips or emergencies when power is out. They do, however, tend to be heavier and more bulky than other types of filters, and they might not be the best choice for hikers who want to travel light or campers who don’t have much room in their packs.
A big plus for this type of filter is that it can retain the beneficial minerals Piped drinking fountains in the water, something other types of filters can’t do. They’re also typically long-lasting and relatively affordable. Some require priming before initial use, so check the instructions (it varies by filter) for details on how to do this.
One downside of this type of filter is that the flow rate is slow. It can take hours for a tank to fill up, which may make it unsuitable for people on a tight schedule or families who want quick access to filtered water. It’s also important to boil any filtered water before drinking it, since a filter isn’t designed to kill all harmful bacteria and other pathogens.
Squeeze Filters
The Sawyer Squeeze is a compact, lightweight water filter with a variety of ways to use it. It’s ideal for backcountry backpacking, international travel and emergency preparedness. It’s easy to use, fits in the palm of your hand and is backed by a lifetime warranty.
To use it, simply fill a 32 Smart water dispenser ounce pouch from a water source and then screw the Sawyer Squeeze on to the end of the bag. Then, either drink directly from the filtered pouch or squeeze the water into another water bottle, hydration bladder or even your mouth (using a straw).
It’s also compatible with most bottles with 28mm threads including many disposable water and soda bottles. It comes with two pouches for storing dirty and clean water and can be attached inline on hydration packs as well.
Like all filters, the Sawyer Squeeze requires regular backflushing and sterilization in the field to maintain optimal performance. This can be done with vinegar or bleach depending on your preference and both work well.
The Hollow Fiber Membrane in the Sawyer Squeeze is also extremely durable and can be cleaned by squeezing out the excess water in the filtration chamber using the cleaning syringe included. This can be repeated a few times for a deep cleaning. It’s also easy to carry and pack thanks to the compact size and collapsible Mylar pouch.
Inline Filters
Generally used in conjunction with gravity systems, some filters like the Sawyer Squeeze system and Platypus QuickDraw can be attached to a hydration reservoir you may already be carrying, offering on-the-go filtration without adding much weight. They work by suctioning water from a pouch or bottle, through the filter and directly into your mouth, and generally require less maintenance than pump filters.
They’re great for backpacking and day trips but can also help keep you hydrated while overlanding or traveling abroad. They’re easy to use and can often filter more liters before needing to be replaced than some other options we tested.
These are more durable than pump filters but can also be somewhat bulky and slow to fill up, making them a little less ideal for fast-paced missions. They typically have a single-stage filter process, which means that the quality of your backcountry water might not be as high as other filters.
Our selection of water filters covers all the basics, with a wide range of sizes, features and price points to fit every backpacker’s needs. We tapped our hydration and gear experts at Good Housekeeping to curate this list of our top picks. Managing Editor Mary Murphy is an avid backpacker who knows the value of a good filter. She curated our initial selection of 14 filters in 2020, and Senior Editor Chris Carter has been scouring the backcountry ever since to bring you this updated list.