Why you should buy this: The MSR Trail Base is one of the most versatile filtration systems on the market. You can use the entire kit as a gravity system or break it apart into a pocket-sized filter and a portable 2L reservoir.

Who it’s for: Campers and backpackers in a group who want to purify two liters of water or more at a time.

Why we picked the MSR Trail Base:

This MSR Trail Base 2L filtration system uses two bags — one for dirty water and one for clean water. The bags work as you would expect — you pour the unfiltered water into the “dirty” bag and use gravity to filter into the clean bag. This dual-bag system minimizes any contamination and helps to keep your clean water clean. It also filters exceptionally fast. The Trail Base hollow fiber filters remove bacteria and protozoans, but not viruses. It cleans easily as well — just shake or swish to remove any debris.

What sets the Trail Base apart from the competing gravity filters by Platypus and Katadyn is the modular design of the Trail Base. You can use the whole kit as a basecamp gravity filtration system or break it apart and use the filter and reservoirs individually. The pocket-sized trail shot filter is outstanding. It has a short hose that allows you to reach even the smallest puddle of water and filters water quickly using the integrated hand pump. It’s fast — we were able to fill a 1-liter SmartWater bottle in under a minute.

The Trail Base is available now with both a 2L and 4L reservoir.  If those sizes aren’t big enough for you, then just wait a little longer — MSR is preparing to release a 10L AutoFlowXL Gravity Filter system in the near future.

Why you should buy this: The Lifestraw is inexpensive enough to be a no-brainer filter to always have in your pack for the SHTF moments.

Who it’s for: Backpackers or travelers who want an easy-to-pack filter that you can use like a straw to sip from a lake or stream.

When it comes to ease of use and pricing, nothing is more approachable than the Lifestraw.

Why we picked the Lifestraw:

Just dip and sip. That is how easy it is to use a Lifestraw. As its name implies, the Lifestraw is a straw with a filter built inside of it. It filters bacteria and protozoans, but not viruses and can filter 4,000 liters (1,000 gallons) of water over its lifetime. You place one end in the water source and use the mouthpiece end to suck up the water. It takes a few minutes of sucking to get a good flow, but once it is working you can get a mouthful of water with each suck. The Lifestraws are prone to clogging so be careful not to such up too much sediment and take the time to backwash after each use. This regular maintenance will ensure you get years of use out of the straw.

Why you should buy this: The Sawyer Squeeze strikes an excellent balance — it’s not too big, not too expensive and is effective at filtering disease-causing bacteria and protozoa.

Who it’s for: Backpackers on a budget who want an effective water filter that is easy on the wallet.

Why we picked the Sawyer Squeeze:

The Squeeze gets its name from the included pouch: Fill the bag up at a nearby stream, attach the filter head, and squeeze the purified water into a container or bucket of your choice for fresh water.  It filters bacteria and protozoans, but not viruses. The pouch collapses easily for great storage when you aren’t using it, making this option particularly backpack friendly.

However, the filter is an adaptable little guy — it has attachments that allow you to fit it over a faucet for purified water during emergencies (or doubtful water quality), or you can use the included bucket adapter to fill a bucket for showers and other more substantial needs. According to Sawyer, the filter gets rid of 99.99999 percent of bacteria and protozoa. It’s a particularly versatile purifier, making it an excellent option if you’re operating on a limited budget.

Sawyer also makes the Sawyer Mini and the Micro Squeeze. They both are smaller versions of the squeeze that are equally easy to use and as efficient as the standard-sized Squeeze.

Why you should buy this: Aquamira water treatment drops are a great alternative when you don’t want to carry a filter or have a filter that fails.

Who it’s for: Backpackers who want a cheap and easy way to sterilize water without having to carry a filter.

Why we picked the Aquamira water treatment drops:

The traditional water sterilizer used to consist of tablets or liquid you put into water to help kill bacteria and make it safe to drink. These chemical treatments aren’t as convenient as filter-based water purifiers, which is why they’ve mostly been replaced on the market. They are still a useful alternative for a couple reasons: They’re cheap, very effective and they don’t take up much room in your pack. Aquamira is our top pick because it uses chlorine dioxide, which kills everything (bacteria, protozoans, and viruses) in the water and doesn’t change the taste or the color of the water.

You can easily buy 1 ounce of Aquamira and store it for an emergency. Because it uses two separate solutions that are inert, the treatment has an extraordinarily long shelf life of four years, even after you open it.  The liquid form also is fast-acting when compared to the tablets. You don’t have to deal with tablets that sometimes are difficult to dissolve and take up to four hours to work. As soon as the Aquamira liquid is activated, the chemicals get right to work on the nasties in your water.

Using Aquamira is a two-step process. You first mix solution A with solution B according to manufacturer’s directions and wait 8 minutes for the chemicals to react and form chlorine dioxide. You then add the chemical mixture to your bottle or bladder and wait for 30 minutes while the dangerous microorganisms (bacteria, virus, protozoa) are killed off.  During this process, the chlorine dioxide is neutralized so they don’t leave a bad aftertaste like iodine does. It takes some planning to get potable water when you are using with Aquamira, but you don’t have to deal with clogged filters or dead UV pens that fail when you need them the most.

Why you should buy this: The MSR TrailShot is surprisingly small and lightweight, yet still very effective.

Who it’s for: Ultralight backpackers looking for a water filtration system that weighs next to nothing and doesn’t add bulk to their packs.

Why we picked the MSR TrailShot:

Weighing just 5 ounces and measuring 6 inches in length, you’re hard pressed to find a filtration system that is this light and compact, yet still highly effective. MSR says that the TrailShot can remove 99.9999% effective at removing bacteria from water, while also 99.99% effective with protozoa too. Additionally, the TrailShot can remove particulates from water, making it even safer and healthier to drink.

The TrailShot requires just one hand to use and can draw water directly from a lake, river, or stream. It is fast enough to fill a 1-liter water bottle in under a minute, yet safe enough that hikers can drink straight from the spout. It is even incredibly simple to keep clean and functioning in the field, which makes it a great choice for extended outings or long-distance hikes. It’s size is so convenient however that mountain bikers, trail runners, and other outdoor enthusiasts will find it handy to carry with them as well.

Why you should buy this: The Platypus GravityWorks

Who it’s for: People who don’t like pumping

Why we picked the Platypus GravityWorks 4L:

This 4L filtration system has an interesting dual-bag setup. Pour water into one bag and it empties into another as it filters, allowing you to control how much water is filtered at one time. Unfortunately, it doesn’t filter water that’s potentially contaminated with viruses but it remains a very strong option for a basecamp that needs a reliable source of potable water. The filtration speed is particularly fast, which is nice if you go through a lot of water while cooking or cleaning. It filters bacteria and protozoans, but not viruses.

Do you need a filter or a purifier?

Keep in mind that when people talk about backcountry water treatment, they mean, “Make natural water drinkable,” and that’s the definition we used here. There are actually two types of water treatment — water filters and water purifiers.

Filters are popular among hikers and backpackers because they are relatively cheap, packable and easy to use. They use a hollow fiber membrane or similar material with microscopic pores. These pores are small enough that they will remove bacteria and protozoans (such as Cryptosporidium and Giardia lamblia) found in mountain rivers, lakes, and similar bodies of water. Filters are convenient, but they require some maintenance. They can get clogged with debris, especially if you don’t pre-filter the water to remove sediment and organic material. To unclog a filter, you need to backwash it periodically according to the manufacturer’s directions.

True purifiers (which are also on our list) tend to use specialized filters, UV light or chemical options to kill viruses in addition to bacteria and protozoans. Viruses often aren’t a significant concern when traveling to remote streams or lakes, but in undeveloped countries, or in rivers where people tend to congregate, virus-killing purification is necessary. Don’t go unprepared or even underprepared when it comes to treating your water in any unsanitary locations.

Besides making water safe to drink, some filters and purifiers also include activated charcoal in the filtration system because it helps to remove unpleasant tastes from the water. It also is effective at removing heavy metals, pesticides, and other industrial/agricultural by-products.

Do I need a backup?

Absolutely, yes! You should carry a backup water treatment when you are going into the woods for more than a few hours. No water treatment is foolproof. We’ve had our filter clog unexpectedly on the trail, accidentally left it outside to freeze and even forgotten to pack it. Having a backup in these circumstances allowed us to continue on our trip and not have to turn back because we couldn’t treat our water. If you travel in a group, you can share the load. As long as two people have a water treatment option, you shouldn’t have any problems with water. If you have no water filters or purifiers and you absolutely need water, you also can boil it for 10 minutes before using it to drink or eat. Boiling is as effective as any of the filters or purifiers, it just takes time and patience.

Storage and care

Treat your water treatments systems with some TLC and they will last you for years. Abuse them and you may end up pooping your pants and puking your guts out from some nasty intestinal bug. During your hike, you need to watch out for two things — any particulate matter that’ll clog your filter or below freezing temperatures that’ll freeze your filters. Preventing particulate is simple — choose a cleaner water source if possible or use a cloth as a pre-filter to remove the sediments and silt. Freezing your filter is a bigger issue during the shoulder season but it can easily be avoided by sleeping with the filter in your sleeping bag.

When you are done hiking or backpacking, you should backwash your filter to remove any debris if recommended by the manufacturer and then sanitize it. You can sanitize it using chlorine dioxide drops or diluted bleach and allow it thoroughly dry before storing.