The Ultimate Guide to Outdoor Water Treatment Devices

Outdoor water filter (indiv.)

Our mission is to get people outdoors, not sell gear. That's why our guide starts with the core function that needs to be addressed, then helps you evaluate your options holistically, since sometimes you may not need any gear & can use what you have at home. We want you to think critically about what you need, which is personal to you with no right answer (some people go venture outside naked without any gear, survive & have a great time).

Core function: Water that comes through the pipes at home has already been treated by a water treatment plant to be potable, i.e., drinkable (in most municipalities in the United States). When you're outdoors, you'll need to figure out if your campsite provides potable water or not (most do). If not, or if you'll be backpacking, you'll need to treat the water yourself! You may wonder, isn't water outdoors safe to drink? Alas in a post-industrial world, it is very difficult to find water that doesn't need any treatment, no matter how remote you are (remember the stories of acid rain moving from one place to another?). Besides, it's a health risk not everyone wants to take! (If you're curious though, just in 2018 there were 2 articles published: the first supporting no filters, one as a rebuttal.) Of course, we always recommend treating water before drinking. For this, you need something much more sophisticated than a standard filter you may have at home (e.g., a Brita), because you're not just filtering for dirt or for taste, but actually trying to treat the water to remove harmful bacterial and/or viruses.

Is either the core function or the outdoor-specific gear made for it an essential?

Either having a water treatment device and/or carrying in enough water is needed for most backpacking trips .

For rationale, read our 'what you really need' protip

What we carry

General Notes

  • We choose what we carry based on extensive research on what's the best value to our customers (e.g., price given performance & durability features) across all the top brands. We specifically do not carry every brand & model; for details on why we do/don't carry certain items in the following What To Use & How To Choose section
  • Buy prices are MSRP with tax, i.e., what you see is what you pay. Prices may differ in-store due to change in models or discounts, but this is rare. If we don't sell what we rent, we list MSRP value with tax
  • Rent prices are the starting prices; enter trip dates on our Catalog to get exact prices (based on total trip length, not per day!). We also don't charge sales tax, an automatic savings of almost 10%!

Of course, we also offer stoves & cookware if you prefer to use heat treatment

Physical filter* Squeeze Gravity
Physically squeeze it Set up the system so that gravity can pull water through the filter
Model MSR TrailShot water filter MSR TrailBase water filter
MSR TrailShot MSR TrailBase (2L capacity)


MSRP with tax

$55 $152
Rent $5+ $14+
Online rental Catalog name Outdoor water filter (indiv.) Outdoor water filter (group)





Carry size & notes Fits in pocket Fits in purse

*As previously mentioned, physical filters are susceptible to freezing. We like the MSR TrailShot/TrailBase because there's an integrity test that can be performed to check if the filter's performance has been compromised

When you rent online, you can select from available options or we'll pick out something for you. You can also write-in any preferences on the last page of checkout. This section describes the majority of our models & options, but sometimes we carry others.

What to use & how to choose

Key factors

Cool zippers, new waterproofing, etc... sometimes it's easy to get lost in all the hype (over-spending happens on features). Our guide focuses on the fundamental factors you should always keep in mind (thus, this short list is similar across all items). Then only at the end do we have some questions to get you thinking about other minor features.

We highly recommend reviewing Type or Style first, where we review what you can use to address the Core function--a regular item you have at home may work! The other factors are secondary & depend strongly on the Type or Style you've picked.

While we encourage you to use regular items wherever possible, as an outdoor gear shop, we only carry outdoor-specific products

Type or Style

We've organized the most commonly used items people use to address the Core function below, with example images, characteristics, features, etc.

Make sure your treatment strategy is effective against what you need to treat, based on what you're going! In the United States and Canada, the biggest concerns are protozoan cysts and bacteria, with common concerns being: giardiasis, cholera and cryptosporidium, dysentery, salmonella, Escherichia coli. Other concerns may be chemicals (pesticides, herbicides, etc.). When traveling internationally to areas where water contamination is a concern, you may also need to worry about viruses, with common concerns being: travellers’ diarrhea, typhoid fever, hepatitis A, hepatitis E, and campylobacter. Each treatment below is commonly used by backpackers in the United States.

Treatment technique Pump (physical filtration)* Gravity (physical filtration)* UV (ultraviolet light) treatment Squeeze (physical filtration)* Straw (physical filtration)* Chemical purification Boiling
Example images Pump filter Gravity filter UV treatment Squeeze filter Straw filter Chemical purification Boiling

Is this good for groups?

Can it treat a lot of water at once?

Usually treats 1 liter at a time (may come with an integrated water bottle)

Some models for example, are designed for individuals to directly drink from

Definitely designed for individuals to directly drink from

Depends on capacity of cookware

How does it work?

Always refer to specific product instructions

Physically pump it Set up the system so that gravity can pull water through the filter Turn it on Physically squeeze it Drink through the straw Add the chemical Boil water
Does it also remove dirt & particulate matter?

Is it relatively quick?***

Time needed to treat ~1 liter (for physical filtration, assume you're working it at optimal speed)

2-4 min 5-7 min 15-30 min Depends on boiling method; you should bring water to a rolling boil for 1-3 minutes, depending on altitude (see Usage section)

Does it protect against viruses?

Again usually only a concern outside the U.S. & Canada

Generally no****
Any other considerations? Susceptible to freezing** Needs power (usually USB-powered with backup batteries) Susceptible to freezing** Since you drink directly, not the best for sharing; susceptible to freezing** May leave a chemical taste (can be removed with secondary chemical treatment) Depends on stove & cookware
Effect on secondary factors Price $80-100 $50-100 $50-100 $20-50 $20 <$0.20 per dose
Several 100L or 1000L treatable, depending on model Each dose may treat ~500mL
Weight & Size Heavier & larger Lighter & smaller
Large variation in weights (e.g., some filters have an integrated drinking bottle)

Why we do/don't carry it

= we rent

= we sell

Usually for very large groups

Standard for most outdoor uses

On our Catalog, this is indicated with '(group)'

We prefer treatment systems that don't rely on batteries

Standard for most outdoor uses

On our Catalog, this is indicated with '(indiv.)'

Usually for individual use, hard to share a straw Takes a long time & may affect taste of water This is not a separate item; we do carry cookware & stoves

*Physical filters may have interchangeable form factors. For example, a straw type may screw into a bottle to become a squeeze type, which may screw into a gravity set-up to turn into a gravity type

**See Usage section for more info

***For physical filtration, you may see a Flow Rate metric. Keep in mind though, that this metric represents optimal circumstances (e.g., doesn't include potential clogs). That's why even though many published rates are around 1L per minute, our time estimates are more realistic based on user feedback

****Some very high end pump filters may remove viruses, but these models would be more expensive than the price range shown


One of life's certainties is the trade-off between price & quality. This creates an inherently unfair situation. If you save money today by buying something lower end, you'll end up replacing it more frequently, spending money & time each instance so that at the end, you probably haven't actually saved anything. On the other hand, if you decide to invest in something higher end, you'll need a lot more upfront money, and you need to be able to use the item frequently enough to make it worthwhile.

We developed our rental program to address this unfairness. We don't sell lower end items. But for our higher end items, we offer them for rent at up to 90% off retail price, generally well below the cost of buying even the cheaper option. That's a win-win!

It may seem like the price & quality trade-off is disappearing, because you can find a cheap version of almost anything for tens of dollars that still has good reviews (assuming the reviews are real). Remember 2 things:

  • Many reviews are written after only a trial use, first use, or infrequent use: We've seen entire review videos of gear done at home, which is very different than actually being outdoors!
  • The point of gear is to give you a good experience because you've already spent money to be on vacation from work! Don't let quality issues affect your relaxation

For gear specifically, the quality issues center around performance & durability.

All that said, water either is treated, or it's not. So price is more a function of type rather than how well it's been treated (i.e., performance). Within the same type of treatment strategy, different products may have differences in durability (e.g., how long a physical filter lasts, or how likely an integrated bottle or water bag is to leak).

Methodology notes on prices shown on this page

Capacity (size)

Water is life! Rule-of-thumb: drink 1 liter for every 1 to 2 hours of hiking. Don't forget, you may also need water for cooking, cleaning, etc. With any trip, you can either bring the water that you'll need, or treat natural water sources. Here's the trade-off:

  • The benefit of bringing water: you're not reliant on nature (a stream may have run dry) & don't have to wait to treat the water
  • The benefit of treating water: you don't have to carry water, which is heavy: 1 liter of water weighs 2.2lbs (1kg)

You'll need to decide based on research for your trip conditions (e.g., where is there potable, filtered water or natural water you can treat relative to your campsite or trail). Often, the decision isn't one or the other, but a combination of both.

The quantity of water you're able to treat at any one time is a function of type of treatment. We especially recommend careful planning for groups. For example, if you have 1 small squeeze filter for a group, treating water for everyone can take a long time if you want to stay together as a group.

Weight & Size (Compactness) for Backpacking

If you're thru-hiking 20+ miles (32+km) per day, every advantage counts! In this case, size refers to compactness. You can carry more gear in the same size backpack if all of it is very compact, or for more weight savings, you can get a smaller size pack.

There isn't a separate comparison table, because weight & size are functions of form factor (see Type or Style), and within each form factor, the industry doesn't then offer 'Superlight' or 'Ultralight' models.

Usage tips

Note that if you anticipate filtering from very dirty sources with high particulate matter, you may want to double-treat: bring a bandana or another strainer to first remove the particulates before passing water through your filter, this preserves the life & effectiveness of your filter.

Choose an appropriate water source

These are the important things to consider (an ironic acronym could be CRUD, since you actually want CRUD-free water, whatever helps you remember it!)

  • Clear - the more clear, the better! Large rivers can often be silty (high in particulate matter), so it's often better to take water from a smaller stream or tributary if available.
  • Running - running water doesn't collect contaminants, avoid stagnant water if at all possible
  • Upstream - move away from trails, roads, or camps to avoid runoff
  • Decontaminated - minimize contamination risk by avoiding areas close to agricultural or animal husbandry or ranching use

For more tips on locating water & also staying hydrated more generally, check out this resource.

Notes on physical filtration: All physical filters are susceptible to freezing. If it freezes, ice crystals can expand and crack the filter cartridge, compromising its effectiveness. Unfortunately there's often no sure way to tell if the filter has been damaged in this way, so it should be replaced. If you believe the temperatures will drop below freezing at night, you should sleep with your filter inside a ziplock bag in your sleeping bag, close to your body heat. That said, always attempt to store your filter away from temperature extremes.

Notes on chemical treatment: When using chemicals to clean your water, try to ensure that the rim of the water container is not exposed to dirty water. If it is exposed, then try to treat it as well: after the chemicals have been added to the water, unscrew your container slightly, shake it upside down, and wait until a some of the water drips through to clean the threads and rim of your bottle. Also note that prolonged use of chemicals to clean water may have consequences on health.

Notes on UV filtration: The most important tip for battery-operated devices: take out your batteries! There are too many stories where the device's on-button was inadvertently pressed, and so it was completely drained by the time it was needed. Not to mention, in cold environments, batteries will drain (you should, in these cases, keep your batteries in an interior pocket, close to your body heat), and in hot environments they can explode (you should also keep them in a pocket in this case, somewhere out of the sun).

Notes on boiling water: Per US Center for Disease Control, "Water should be brought to a rolling boil for 1 minute. At altitudes greater than 6,562 feet (greater than 2000 meters), you should boil water for 3 minutes".

Notes on the MSR Trailshot filters that we carry! Sometimes the filter can seem to run really slow or water can leak out from the bulb. We realize these issues can be hard to troubleshoot, so we have published the training videos we use on how to check-in the filter. We strongly recommend reviewing before taking these filters into the backcountry. Note, the same videos apply to the MSR Trailbase filter, since it uses a Trailshot as its core filtration system.

Maintenance tips


Most issues that arise are not reparable (e.g., a crack in the filter) and will require a completely replacement (though for some models, it's possible to replace just the filter cartridge rather than the whole product). If just a small superficial piece is missing, you may check with the manufacturer to see if you can replace just the part (usually applies to lids or rubber gaskets used to prevent leaking).


For physical filters: you should clean after each trip at least. Follow manufacturer guidelines, often this will be backwashing a few times: forcing cleaning water through the filtration system backwards to get rid of clogs or trapped impurities. Even if the first backwash looks clean, don’t be fooled as sometimes there is dirt lodged further inside.


Don't put it away or close any lid(s) until it's fully dry

For Physical-filters: There is often water lodged inside the filter. Do your best to rigorously shake it out, dislodging as much water as possible. If there are any components like a water bag, follow the procedure to maintain those here

For UV-filters: If it's battery-powered, follow standard storage procedure for any battery-powered device:

Minimize battery leak & risk of corrosion by storing batteries outside of the device in a cool, dry, dark place

We have a general protip on how to store & maintain gear that we highly recommend reviewing as well. If you send us video or a good photo series, we may be able to help you evaluate your repair needs.

The exact numbers (e.g., weights, dimensions, prices, etc.) used were updated as of September 2019 . That said, there usually isn't dramatic change; we update & review the market roughly biennially.

Thoughts, ideas, questions? Let us know in the comments below! We're Last Minute Gear, the only outdoor gear shop where you can buy, rent, or borrow gear!