How to Choose The Best Backpacking Water Filter

How to Choose A Backpacking Water Filter

Of all the items on your backpacking packing list, the one item you don’t want to cut corners with is your water filter. When you’re hiking all day, you need a lot of water to keep your body properly hydrated. Unfortunately, in the back country there aren’t any water fountains or sinks to fill up your bottles. You need to grab your water from a lake or river and filter it yourself. Since natural sources of water can contain bacteria and protozoa that will get you sick, you want a trustworthy piece of gear for this task. Knowing how to choose a good backpacking water filter is important.

You can find our picks for the best backpacking water filters here. But if you prefer to do your own shopping and searching, you can use our tips below to learn how to choose a backpacking water filter for yourself.

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Water Filters Vs. Water Purifiers

Before we dive into how to choose a backpacking water filter, we need to cover the difference between a water filter and a water purifier. Some people use these terms interchangeably but doing so is not accurate. There are some important differences between filters and purifiers.

Water Filters

A water filter contains a cartridge or element that has microscopic pores to physically strain out protozoan cysts and bacteria. It’s kind of like a strainer, but on a microscopic level.  Everything over a certain micron size is captured by the filter, removing harmful particles from the water. This also helps with removing gross stuff like dirt, bugs, and vegetation from it.

However, due to the incredibly small size of virus particles, viruses are not effectively removed by most filters. That’s where purifiers come in…

Water Purifiers

A purifier will use chemicals or ultraviolet light to kill viruses and harmful bacteria in the water. For most water sources in North America, this next-level protection isn’t entirely necessary. Viruses such as norovirus and Hepatitis A typically aren’t found in natural water sources here.

However, if you are traveling to less-developed areas of the world or are going to a particularly high traffic area, you might want to consider purifying your water instead of simply filtering it. The downside of doing so is that a purifier won’t remove sediment from the water, so floaters and dirt will remain in it.

Different Needs for Different Sources

How you choose a backpacking water filter may vary depending on what kind of water sources you will be pulling water from. Some sources of water will require more thorough cleansing than others.

• Clean Sources– If you’re hiking in the mountains and gathering water from alpine streams or high elevation rivers, you can use just about any type of filter. This water tends to be clean especially in remote areas. You still wouldn’t want to drink directly from the source, but a purifier is not necessary.
• Murky Sources – When you need to grab water from ponds, lakes, and other still sources of water, you’ll want to always use a filter. If you plan on using a purifier, you should pre-filter the water in order to remove sediment. Water from these sources tend to have vegetation, dirt, and small organisms floating in it that can make the water a bit, well, gross to drink.  
• Questionable Sources– In North America and other developed parts of the world, finding viruses in the water is not as big of a concern. However, if you travel overseas, you should bring along a purifier. You may not know the quality of the water from natural sources and may expose yourself to harmful diseases if you are not careful.

Different Types of Water Filters

Pump Filters

A pump water filter uses a manual pump device to push water into a hose, through a filtering system, and into a water bottle. These are fantastic for pulling water out of shallow water sources like creeks and streams. You can also filter a good amount of water rather quickly. However, backpackers may avoid these pumps because they can be physically tiring to use and are rather heavy compared to other types of filters.

• Pros: Can gather water from shallow sources and is fast.
• Cons: Expensive, physically tiring, and heavy.
• Our Favorite Pump Filter: MSR TrailShot Filter

Bottle Filters

These water filters are incredibly simple and easy to use. Simply dip the bottle into the water source to fill it up, then screw on the filter cap and drink. As you drink, the suction of your mouth pulls water through the filter. This is great for getting a bottle’s worth of clean water quickly and easily. However, if you’re going backpacking and need to store a lot of clean water, this isn’t as effective. Bottle filters are more fitting for a day hike or a trail run.

• Pros: Easy to use and lightweight.
• Cons: Only filters a bottle’s worth of water.
• Our Favorite Bottle Filter: Katadyn BeFree Filter

Squeeze Bag Filters

The most popular filters among backpackers are squeeze bag water filters. We love them because they are easy to use, light weight, and very affordable. To use a squeeze bag filter, you fill the bag with water then attach the filter to the top. When you squeeze the bag, it forces the water through the filter and into your water bottle or directly into your mouth. This does take a bit of work and time, especially if you don’t clean the filter regularly.

• Pros: Lightweight and affordable.
• Cons: Requires some effort and bag may puncture.
• Our Favorite Squeeze Bag Filter: Sawyer Squeeze Filter System

Straw Filters

If you like the idea of drinking straight out of the lake, a straw filter is ideal for you. Dip the straw into the water source and start sipping. That’s all there is to it! The downside is that you can only drink water when you are at the water source, you can’t store filtered water to drink throughout the day. This makes them great for trail runners or day hikers who want to carry as little weight as possible. Backpackers, however, will be better off with a bottle filter or a squeeze bag so they can carry the clean water with them.

• Pros: Ultralight and easy to use.
• Cons: Can only drink water when you’re at the source.
• Our Favorite Straw Filter: LifeStraw

Gravity Filters

The ideal water filter for a small group of backpacker is a gravity filter because of it’s ability to filter a lot of water with little effort. These filter systems come with 2 reservoirs, one for dirty water and one for clean water, and a hose with a filter that connects the two. When you hang the bags, the water from the dirty bag flows through the hose, through the filter, and into the clean bag.

The process requires a deep water source to fill the reservoir entirely and takes some time, so it isn’t ideal for filling up at a quick stop at a river crossing. It is great, however, for letting water clean itself as you relax at your campsite.

• Pros: Low effort and filters a lot of water.
• Cons: Expensive and requires a place to hang the bags.
• Our Favorite Gravity FIlter: Platypus GravityWorks Filter System

UV Purifier

A popular, reusable option for purifying water is a UV purifier. Unlike a chemical purifier, you can reuse a UV purifier over and over again. To use, fill your bottle up with water, stick the UV light into the water and turn it on. During a short wait, the light kills off viruses and bacteria in the water.

These are super simple to use and are fairly lightweight. However, they do run on battery power, which can be risky to rely on when you’re out in the backcountry. The potential for malfunction means that you’ll need to carry along a reliable back-up filter or purifier.

• Pros: Fast and easy.
• Cons: Expensive, isn’t ideal for murky water, and has the potential for malfunction.
• Our Favorite UV Purifier: SteriPen UV Purifier

Chemical Purifier

A simple and lightweight method for purifying water is to use iodine or chlorine-based purification tablets. All you need to do is drop them in your water and wait. You’ll have to wait 30 minutes for it to kill bacteria and viruses and 4 hours for it to kill cryptosporidium.

This wait time makes it the slowest of the filter and purification methods, but it is also the most foolproof. You can’t break, clog, or rip chemical treatments and you don’t need to do any maintenance. These qualities make chemical purifiers great backup purifiers to keep in a first aid kit for emergencies.

• Pros: Low maintenance, easy to use, ultralight
• Cons: Takes a lot of time and does not improve the taste of the water.
• Our Favorite Chemical Purifier: Katadyn Micropur MP1 Purification Tablets

Boiling Water

A classic method for purifying water is to boil it. Since most backpackers bring along a backpacking camp stove to cook their meals with, boiling water is a great back-up option for when filters or purifiers fail in the field.

However, it isn’t ideal as a main method of purifying water. It takes a decent amount of set up and is time consuming. Not only do you need to wait for the water to boil, but you need to wait for the water to cool before you can put it into your bottle or reservoir. For rehydrating meals, boiling water is perfect for getting your water hot and clean for your meal.

• Pros: Efficient for purifying water for meals.
• Cons: Time consuming and doesn’t filter out floaters.

Important Qualities in a Filter or Purifier

When you’re trying to choose a backpacking water filter, there are a few important qualities you should be focusing on:

• Weight: For backpackers and hikers, pack weight is always at top of mind. Some filter options are ultralight while others can be rather heavy. If pack weight is a concern for you, a squeeze bag or bottle filter may be a better fit for you than a pump or gravity system.
• Ease of Use: For some backpackers, having a system that is easy to use is of the utmost importance. If you are a beginner backpacker, you might gravitate more toward a gravity or bottle filter which do most of the work for you.
• Pore Size: If you’re using a filter, not a purifier, then the pore size of the filter should be taken into consideration. The smaller the pores, the smaller the particles the filter will remove. For protozoa, the pores need to be 1 micron or smaller. For bacteria, it needs to be .4 micron or smaller₁. Be sure to choose a filter with small enough pores to filter out both protozoa and bacteria.     
• Flow Rate: The flow rate of a filter is the speed at which it filters water. This is often measured in liters per minute and you can often find it written on the filter packaging. Keep in mind that this estimate is measures based on optimal circumstances and will decrease with time. The faster the filter, the less time you will need to spend filtering your water every day.
• Filter Life: When deciding how to choose a backpacking water filter, price might be a concern. While it’s certainly valid to consider the cost between two brands, be sure to also consider the filter life. A cheaper filter that you need to replace every 5 trips will end up costing you more than an expensive filter that will last you 10 trips.
• Maintenance Required: All filters need to be cleaned or backflushed after use to prevent clogs and maintain the optimal flow rate. Some filters require more extensive maintenance than others. Be sure to consider all the pieces of the full filter system that will need to be cleaned and make sure you are up for the task.

Maintaining a Water Filter

Every water filter will come with directions for proper care and cleaning. Some filters will require backflushing in the field, others may require running cleaning solutions or soap through them after each trip. Be sure to follow the instructions for the specific filter that you purchased.

It’s important to stay consistent with these cleaning practices to get the full life out of the filter and keep up the flow rate. In the long run, proper maintenance will save you time and money with your backpacking water filter.

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