Proper hydration is crucial for an enjoyable trek outdoors. But trying to carry water for extended trips is exhausting. This is because one liter of water weighs about one kilogram (2.2 lbs). The problem with drinking from stagnant backcountry water sources is they are dangerous. Due to the presence of harmful water-borne pathogens. To prevent you from harm one solution is to select a backcountry water filter. Proper water filtration is vital to make water safe for drinking.
Don’t know where to start? Don’t worry, in this article you will learn how to select a method for outdoor water-treatment.
Keep these factors in mind to select a backcountry water filter or another water-treatment method:
- The importance of clean water: Learn what types of risks (pathogens) lurk in backcountry water sources.
- Water filters vs. purifiers – What’s the difference?
- Function of water filters and purifiers.
- Pre-filter accessory – Valuable for murky water sources.
- Types of water filters and purifiers – With pro’s & con’s.
- Shopping tips
- Backcountry Water Treatment Best Practices
Outdoors Informed is reader supported. We independently research and rate every product. When you buy through a link on our site, we may earn an affiliate commission. However, our opinions and evaluations are our own. Outdoors Informed does not accept free products from manufacturers. Learn more
Why Clean Water Is Important
Water is important because it makes up 70% of our total body weight, and a startling 90% of brain weight. For people who spend extended periods of time in the backcountry finding clean water can be an issue. In the backcountry many water sources aren’t safe to drink without treatment.
We are seeing less available clean water sources because more people are enjoying the backcountry and the outdoors in general. More travelers in the backcountry means water sources see more contamination. In general, it’s easy to identify sources of contamination, like humans or wildlife. Animals and humans risk water due to their fecal matter getting into the water, transmitting pathogens.
But there are also contaminants floating in water that are invisible to the human eye. In North America, there are two main categories of pathogens that are big concerns. One is bacteria and the other are protozoan cysts. Whereas in developing countries, more serious risks of viruses like Norwalk are evident.
To help you better understand the dangers of pathogens I will give a brief explanation of some below. Plus which water treatment system can remove them.
Pathogens are microorganisms which cause disease. All a pathogen needs to survive and thrive is a host. Waterborne pathogens get transmitted a by drinking untreated water.
These are single-celled organisms transferred through human and animal fecal waste. Examples include E. coli, Salmonella, and Campylobacteriosis. Bacteria are the easiest types of pathogens to filter out of water. For size, bacteria are a bit larger than protozoans and up to 100 times the size of viruses.
Ways To Remove Bacteria: All systems of filtration and purification are effective.
These are single-celled organisms that can live and multiply inside your body. This type of pathogen can cause serious intestinal problems. With symptoms developing from two days to a couple of weeks from ingestion. Protozoa survive in cool water for weeks and up to months at a time.
Protozoa has two of the most feared illness causing sub-types : Giardia and Cryptosporidium.
- Giardia is a microscopic parasite transferred via feces in drinking water. It causes an infection in your small intestine called Giardiasis.
- Cryptosporidium is a microscopic parasite that causes a diarrhea disease known as cryptosporidiosis. It has a hard protective outer layer, making it resistant to many methods of water treatment. In fact, it’s the leading cause of waterborne disease among humans in North America.
Removing Both: boil water, UV light, purifier (.004 microns), filter (.210 microns). Plus one type of chlorine dioxide drops (Aquamira Drops).
Remove Giardia but not Cryptosporidium: Chloride dioxide and halogens like Iodine tablets.
These are serious infectious microbes, examples include Hepatitis A, Norwalk and Rotavirus. They are 0.004 to 0.1 microns in size, which is about 100 times smaller than bacteria. Due to their size, water filters are ineffective for water treatment. Purifiers with pore sizes under 0.02 will work. For hiking and traveling in the backcountry of U.S. and Canada, viruses aren’t a significant threat in water. Whereas for international travel in developing nations, they are a big concern.
Effective Treatment Methods: All water treatment methods except filtration.
Water Filters Versus Purifiers
To buy a backcountry water filter or purifier, you need to confirm it will perform for your intended use. The difference between a water filter and purifier is the size of the pathogen each combats.
Water filters remove only bacteria and protozoan cysts (Cryptosporidium and Giardia). These waterborne pathogens are the main concerns if you’re in the U.S. and Canada. It’s best to keep a micro-filter (.210 microns) in your backpack for backcountry treks.
In contrast, purifiers main purpose it to neutralize viruses, but can stop protozoa and bacteria as well. A virus is too tiny for most filters to be effective to catch. A purifier is a bit of overkill for domestic use in the backcountry. It’s better used for traveling to developing nations with questionable water sources.
One thing that both water filters and pump-style purifiers include is an element called activated carbon. Found inside after the filter element, activated carbon is effective at removing unpleasant tastes. It also reduces contaminants like pesticides and other industrial chemicals.
How Backcountry Water Filters and Purifiers Work
Every water filter and some purifiers include an internal element to treat the water. In general, a water filter works via physical or mechanical force to clean water. Whereas a purifier uses a system to neutralize bacteria, protozoa, and viruses. But doesn’t remove anything from the water. Basic purification will contain silt and debris after cleaning water. As a result, it’s not a great option for cleaning turbid water.
Water Filter Function
For a water filter, it’s function isn’t to kill pathogens, but to capture them inside the internal filter. This internal filter looks like hundreds of tiny straws that get bundled together.
There are four basic types of water filters, but they all work the same basic way. Contaminated water somehow gets drawn into an inlet and pushed through a filter material. This filter uses its tiny pores to trap any microorganisms that are living in the water. After capturing the pathogens, clean water passes through to an outlet for safe drinking.
To determine the effectiveness of a water filter you need to know the pore-size. This is the measurement of the size of the filter pores inside the water filter shown as microns. One micron equals 1/1,000 of a millimeter. To capture protozoa, you need a filter with a pore-size of at least 0.2 microns. For bacteria the filter must be less than 0.4 microns.
A big bonus for users of water filter is that they are effective for both clear and turbid water sources. Likewise, it’s fine to select a backcountry water filter for adventures in most of North America. But bear in mind that it can’t protect against viruses. Be cautious if you are traveling abroad.
Current Types Of Filter Materials
There are three common filter materials you will come across in current water filters. These are ceramic and hollow fiber, below is a simple explanation of each.
Ceramic: This is one of the oldest filter materials on the market. In general, it’s made from a fine silica powder most know the material as diatomaceous earth. It’s inexpensive to make and lasts a long time but is easy to clog the filter. Although it’s easy to clean by scraping off debris and back-flushing the filter. Today, brands include carbon into this filter type to combat heavy metals in water.
Hollow Fiber: Is the filter material that looks like tiny straws bundled together. The straws are actually tiny hollow U-shaped tubes. In this filter, water passes through tiny pores and into the core. Which strains out harmful pathogens and particulates. Hollow fiber works like a ceramic filter but is lighter weight and has a better flow rate. You can back flush this type to clean but over time it clogs to a point where it needs replacement.
Fiberglass: Manufactured from 100% borosilicate glass it does a good job of filtering. Brands use fiberglass because it’s cheap to make and its lightweight. Look for fiberglass used in combination filter systems. One brand uses ceramic for a prefilter, fiberglass as the main filter and carbon for third filter. As a complete system, this is very effective in the backcountry.
Water Purifier Function
A water purifier is different because it’s function is to neutralize viruses. The microscopic size of viruses are too small for most filters to be effective to capture. A bonus with a purifier is it can eliminate bacteria and protozoa too.
You want a water purifier for traveling outside of North America. Keep in mind, that even some domestic backcountry users prefer purifiers. In this case, I recommend you look for ‘clear’ water sources. If clear water isn’t available in your area, use a prefilter before using purification.
The two main systems purifiers use are chemicals like iodine, or ultraviolet light. An explanation of each are below.
Chemicals & Halogens
Used for decades, chemical purification comes in either chemical tabs or halogen drops. The most common types are chlorine dioxide tabs or iodine drops. These work by placing the recommended dosage into the water and waiting. Expect it to take around 30 minutes to 3.5 hours dependent on many variables (ex. temperature of water). Bear in mind, chemicals can’t remove silts or other debris. Some users don’t like the taste of chemical purified water.
Note: Protozoa cryptosporidium is resistant to chemicals like chlorine dioxide and halogens (iodine). Plus, these are a concern for pregnant women and users with thyroid problems.
Ultra-Violet (UV) Light:
This purification method seems like weird science but it’s in fact simple for the user. UV light exposes pathogens, like bacteria, viruses, or cysts to germicidal ultraviolet wavelengths. These wavelengths deactivate harmful living organisms in the water. However, it won’t remove debris from water, add chemicals, or remove bad tastes or odors.
A UV purifier works by placing the device (wand/pen shaped) in water and moving it around to “zap” out the contaminants. These devices usually operate off batteries so ensure you have extra power for your trip.
Note: Multicellular parasites (worms) will survive UV light water treatment.
What Is A Prefilter?
A prefilter is an integral part of some water treatment systems and a bonus accessory for others. Another word for a prefilter is a sediment filter. Sediment is the term for the particulate matter in water that isn’t liquid. As you may have guessed, the function of a prefilter is to remove sediment like silt or leaf debris.
Another function of a prefilter is to remove turbidity from water. Turbidity is a cloudiness in water due to the heavy presence of suspended solids. This is what causes water to appear to be yellow, orange, or brown.
You find a prefilter on many pump-style water treatment systems. Although some brands, make you buy one separately. Below are 5 reasons to consider adding a prefilter when you select a backcountry water filter:
- Aids in maintaining a pump-style water filter/purifiers’ flow rate.
- Reduces field maintenance.
- Prolongs internal component’s life expectancy.
- Improves chemical water treatment effectiveness.
- Essential for UV water treatment in turbid water.
Types of Water Filters and Water Purifiers
To choose a backcountry water filter or purifier it’s important to know which type is best for your needs. This can be confusing due to the vast amount of types of water filters and purifiers. To add to your confusion, as brands innovate they are producing hybrid types.
So, use the simple explanations of the 8 basic types of filters and purifiers below as a starting off point. Included are the pros and cons of each, ideal uses in the backcountry plus example models.
1. Pump-Style Water Filters and Purifiers
These are the traditional and popular types of water treatment in the backcountry. With these types you first drop the intake hose into a water source. Second, you attach or place the outlet hose into your water bottle.
To clean the water you pump a handle which siphons dirty water into the intake hose and through the filter. The filter strains out microorganisms and debris in the water. Next this clean water flows through the outlet hose into your bottle. A pump-style purifier, is a combo of a filter and purification system. It operates the same as a filter. Bear in mind, pump mechanisms differ between brands as do the flow rates.
- Allows you to clean the exact amount of water you need.
- Provide the ability to reach and pull from shallow water sources.
- Dependable with simple operation.
- Cheap long term because you can replace internal filter or cartridge.
- Pumping takes effort, which is in short supply after a long day trekking.
- May need filter maintenance out in the backcountry.
- Heavier and bulkier than other types.
2. Gravity Water Filters and Purifiers
Gravity water treatments are best for people who don’t want to use effort to pump clean their water. It uses the actual weight of the water to perform the treatment.
To use in the backcountry you connect each element together. Fill the reservoir with dirty water and hang it up high from a tree or rock. In use, gravity draws the water down and through the filter to capture the pathogens. This water then flows through an out-take hose to a storage reservoir for consumption.
- You let gravity do all the work.
- Great for cleaning large quantities of water at once.
- You can replace the filter element for cheaper long term use.
- Must have a high place to hang reservoir.
- Cleaning process is slow compared to pump-style water filters.
- Difficult to use shallow water sources.
- Expect to do field maintenance of filter element.
3. Bottle-Style Water Filters and Purifiers
This type of water treatment has a built-in filter or purification system. It’s a simple method to clean water via three different processes. One is like a two piece French press that pushes water through a filter to clean.
A second uses suction from a bite valve to pull water through a treatment element in the bottle. Third is to use a UV light inside the bottle.
- Cleaning method is simple and quick to be drinkable.
- Bottles are lightweight and easy to pack.
- You can replace filter inside.
- Beneficial minerals remain in the water.
- Cost less than pump-style and gravity water filters.
- French press method takes effort.
- Bottle size limits amount of clean water.
- Expect maintenance of filter element out in backcountry.
4. Squeeze-Style Water Filters
Like a bottle filter, a squeeze-style water filter uses your ability to squish a pouch to get clean water. With this type you fill a soft pouch reservoir with dirty water and screw on a filter at the opening. Next you squeeze the pouch to push the water through the filter into your mouth.
- Easy to use.
- Large versions double as a gravity filter.
- Super easy to pack.
- Cheaper to buy than pump-style and gravity specific systems.
- You can replace the filter instead of entire unit.
- Pouch size limits amount of clean water available.
- Flow rate is slower compared to other types.
- You need a separate vessel if you want to store the clean water.
- Filter may need cleaning out in the backcountry.
5. Straw-Style Water Filters
This type of water filter is a small portable device that clean water on-demand. It consists if a hollow straw-like tube with a filter in the middle. It’s powered by your own sipping force, just dip the straw into the water source and drink.
- Super simple use.
- Decent size for packing.
- Costs and weighs less than gravity and pump-style filters.
- You only get clean water if a source is available.
- Will need to clean filter during your trek as it gets plugged up fast.
- For solo use only.
- Some brands don’t have replaceable filter elements.
- Don’t expect this type to filter heavy metals.
6. Chemical Purification – Tablets and Drops
A chemical purifier cleans out water by adding a chemical to it. The advantage of the chemicals they kill viruses plus bacteria and most protozoa. The most common chemicals are chlorine dioxide tablets like Aquamira and iodine drops. Iodine is an effective chemical treatment but leaves a bad taste and dirty color in the clean water.
To use iodine, you drop the chemical into a bucket or bottle of water and wait as predetermined amount of time. Expect to wait at least 30 minutes up to 4 hours for purified water. If you hate the taste iodine leaves behind, try the popular Aquamira chemical treatment. This is a two part system that uses chlorine dioxide. Chlorine dioxide is iodine and chlorine-free.
Keep in mind, iodine doesn’t kill the protozoa called Cryptosporidium. While chlorine dioxide has trouble killing Giardia, another type of protozoa. Both are harmful pathogens found in North America. It’s best that if you use chemical purifiers to prefilter water first.
- Simple to use, drop in and wait.
- Kills viruses.
- Awesome for ultra-light hiking/backpacking applications.
- Small and lightweight packaging.
- Great water treatment backup method or extra survival gear to have in your pack.
- Expect long treatment time periods. From 30 minutes to 4 hours depending on water temperature (colder = longer).
- Iodine isn’t effective against Cryptosporidium, but kills other types of protozoa.
- Pregnant women and those with thyroid conditions shouldn’t use Iodine.
- Some chemicals add unnatural taste to water
- Chloride dioxide tabs have trouble with Giardia protozoa.
7. Ultra Violet (UV) Light Water Purifiers
UV purifiers are pen-like devices that “deactivate” harmful pathogens via germicidal wavelengths. By stirring the UV wand in the dirty water it neutralizes viruses, bacteria and protozoa. They operate by batteries and are simple to use. But it doesn’t remove debris or turbid water. Which is the reason it isn’t great for backcountry use without a prefilter. It’s a better product for simple purification during international travel.
- Easy to use and quick to purify water.
- No field maintenance or replacement of internal elements (beyond batteries).
- Batteries need replacing.
- Effectiveness decreases in turbid water.
- Can’t strain out particulates.
- The need to add a prefilter for best performance.
- UV purifiers tend to be damage easily and are unreliable for long term use.
- Can’t treat large amounts of water with many treatments.
Ex: SteriPen Ultra
8. Boiling Water
For backcountry enthusiasts with a stove, fuel and a pot, boiling is a foolproof treatment. In fact, this is an effective method to combat kill viruses bacteria and protozoa.
It’s simple, bring your water to a rolling boil for 1 minute if near sea level to purify water. Or if you’re above 6,500 feet (1,981 m) doing some alpine hiking or backpacking, you need to boil it for 3 minutes. If you use a murky/ turbid water sources or one with a lot of debris, it’s best to prefilter water before boiling.
- Most simple and effective method of purification.
- Works fine with turbid/murky water sources.
- The Best backup method if your main filter/purifier breaks.
- More time-consuming to bring water to a boil than filtering.
- You have to wait for the water to cool before drinking.
- If it’s your only treatment method, plan to pack extra fuel.
- Doesn’t remove debris.
5 Shopping Tips To Select A Backcountry Water Filter
Beyond knowing what type of water filter or purifier to buy. You need to think about some user factors to select a backcountry water filter. Below are 5 tips to help you make the best choice for your use in the backcountry.
1. Determine where are you going to select a backcountry water filter
Before you head off into the backcountry, it’s critical to determine where you are going. Using a water filter will work for most adventures in the U.S. or Canada. But, if you travel to the backcountry of another country, a purification system is the best option.
Another consideration for where you plan to go in the backcountry is water taste. Imagine trekking in the alpine backcountry and searching for water. Treating water from clear cold mountain streams isn’t an issue as it tastes great. But what if all you can find is shallow turbid water? In this instance you need either a water filter or prefilter with purifier.
As mentioned before, some water filters and purifiers come with activated carbon. Keep in mind, activated carbon becomes ineffective before an actual filter. In general, this type of element lasts for 6 months or 175 liters of use. If taste is an issue look for products that allow you to buy a separate activated carbon element. This makes regular maintenance much cheaper.
2. Compromise Between Weight & Flow Rate
Most gear decisions in the backcountry are a compromise between weight and performance. As you travel deeper into uncharted territories water becomes more scarce and fatigue becomes an issue. As a result you want to find a happy medium between keeping you pack light and having on-demand clean water. Try to match the weight of the system and with your preferred “flow rate.”
Weight is an important factor because every ounce adds to your total fatigue throughout the day of trekking. The weight of the water treatment depends on the design, and the construction materials. In general each type weighs as follows:
- Chemical drops or tablets are around 3-6 ounces.
- Straws, bottles and squeeze-style filters are about 2-3 ounces.
- Pump-style and gravity filters are the heaviest ranging from 11 to 17 ounces (1 pound).
You get the best hydration in the backcountry via quick and easy water treatment. This is why flow rate, or the speed at which water gets cleaned, matters. You will see it shown as “flow” in liters per minute from most manufacturers. Below of is a chart of general flow rates:
With chemical purifiers there isn’t a flow rate in particular. For most expect it to take between 30 minutes up to 4 hours. Bear in mind, manufacturers use best circumstances to test flow rates. The actual flow rate you experience tends to be a bit slower in the backcountry.
3. Decide What You Are Doing
Picking an activity is a big help to select a backcountry water filter or purifier. Which makes perfect sense as different activities call for different water treatment methods. To help you below are some typical backcountry activities and suggestions for which type of treatment to use.
Considering that you will have to pack in everything you need for camping in the backcountry weight and ease of packing is crucial. For camping closer to civilization, a small group can rely on boiling or pump filters. But if you or your group love trekking deep into the backcountry, your best bet is a gravity filter for base camp. Plus some single person bottle-style water filters for day treks from camp.
Ultra-Lightweight Backpacking or Thru-Hiking:
Ultra-light backpackers or thru-hikers have different needs than campers. These users search for the lightest weight gear they can. If you trek hundreds of backcountry miles, pick a chemical treatment. It’s best to add a small prefilter if you prefer water without debris in it. If you don’t like the taste of chemical purification try adding an effervescent vitamin C tablet after treatment.
Although, if you’re backpacking for a couple of days in a medium to large group, you can split the water treatment duties. Use a pump filter or few large squeeze water filters. These are easy to pack and deliver decent flow rates.
For an activity like trail running you want to choose the lightest and safest options. Some may pick a chemical treatment but expect waiting for over 30 minutes before clean water. I prefer bottle-style or small squeeze water filters for instant drinkable water. These are lightweight and durable if you trip and fall.
Planning an epic trip climbing up the mountains? If so you know weight is the biggest factor for choice of water treatment. In the alpine you have a better chance to come across clear water sources than you would below the tree line. This is because sub-alpine areas have more wildlife to contaminate a water source.
For this activity you can rely on a water filter like a straw or squeeze filter on the go. While using a pump or gravity filter at base camp. Another option if you want to go for ultra-lightweight is to use chemical tablets or a UV pen. But bear in mind with UV you need to account for batteries which add precious weight.
With bike packing it’s going to be about weight, but also flow rate. Cyclists depend on quick re-hydration while riding. They need to be able to get water via one hand so bottle water filters are the best option. Or if you prefer your current bike specific water bottle buy an inline water filter adapter. These fit onto your bottle, keep extra weight to a minimum and are small to pack.
International Travel & Camping
If you are overseas and want to camp in the backcountry, take chemicals or a UV pen with a prefilter. The same goes for basic international travel. There are viruses abound in these areas, so it’s essential to protect yourself from them. Nothing’s worse than a trip ruined by stomach sickness.
3. Consider The Water Sources You Will Encounter
Before you trek into the backcountry, it’s vital to research the water sources. You need to plan where water sources might be, and what this waters’ quality is like. Depending on the time of year the depth and quality of water sources will change. Late autumn, winter and early spring are periods when water is usually plentiful.
Whereas if you plan an expedition in late spring or summer may pose possible issues. If the source is a lake or deep pond you should be able to draw water from it. But if you trek above the tree line or rely on water sources fed by snow melt, by this time they could dry up. Regardless it’s a good idea to keep an emergency product like a straw filter in your pack.
Another important consideration to bear in mind is the distance between water sources. If water sources are few and far between you need to bring water storage gear. Remember water is heavy, plan smart to reduce fatigue.
What Is Turbid Water?
Turbid water is cloudy or murky. It’s caused by particles suspended or dissolved in water. As light hits the water it crates a pattern of light making the water appear cloudy or murky. Particulates include sediments like clay and silt, algae, and other microscopic organisms.
Turbid water is serious problem in the backcountry, especially in desert terrain. It will clog filters and lowers the effectiveness of chemicals and UV purifiers. A good idea if you hike the in areas with turbid water is to bring an extra plastic bag. Fill this bag first with the water and let the sediment settle to the bottom. The process can take about 30 minutes. Next, ladle water from the top of the bag to your filter or another bag for purifying. Doing this increases the performance of your water treatment and reduces filter maintenance.
4. Consider Filter Cartridge Life & Maintenance
The main consideration for filter life is cost. Keep in mind, you need to pay the initial price of the unit plus the cost of replacing filters over time. While some water filters may cost less new, these same filters can have a lower life expectancy.
Another consideration is how much maintenance you want to do out in the backcountry. If you have no issue with regular cleaning and back-flushing, then a filter is a good choice. A straw filter need a quick blow to clean, while squeeze models use a syringe. For pump filters the process is more complicated.
If you prefer packing light without field maintenance, purification is best. Keep in mind though if your terrain has turbid water you may need to pack a prefilter, which needs a bit of cleaning.
5. What are you willing to spend?
If you want the cheapest water treatment possible you are going to buy chemical tablets or drops. Going this route has three main caveats. First it changes the natural taste of the water, second it doesn’t remove debris and third it takes time. You could try a straw filter but with this option you limit water treatment to a single person and short trips.
Mid-range priced options include squeeze and bottle style filters. These are great for small groups and solo use but need field maintenance.
The more expensive options include some pump-style and gravity filters. In fact some can reach up to hundreds of dollars like the MSR Guardian, a military grade of water filter.
Combine these five tips and use proper judgment to find the right compromise for your use.
Backcountry Water Treatment Best Practices
We all love the backcountry and it’s our responsibility to take care of it. It’s vital that you follow the “leave no trace” (LNT) rules for protecting our planet. These are the most pertinent ones for backcountry water sources.
- Ensure defecation at least 200 feet (60.96 m) from any water sources. Remember, fecal matter carries bacteria and other potential harmful pathogens.
- After defecation, you need to bury it. For multi day trips I recommend packing a folding shovel. You need to bury solid human waste at least 6 to 8-inches deep. At this depth, bacteria will decompose your waste, and compost it into earth matter.
- If you bring bath tissue or hygiene product make sure you pack them up and out.
- To avoid getting sick, wash your hands after relieving yourself. Use a small amount of biodegradable soap and water. This is crucial if you’re cooking for yourself or for a group of people. Post meal-time do your best to scatter old dishwater.
By now it should be evident that self water treatment in the backcountry is risky but achievable. In the U.S. and Canada you need to protect yourself from bacteria and protozoa. You have a wealth of choice between filters and purifiers. For international travel you need a to protect from viruses. In this instance you need purifier, but it’s best to add a prefilter too.
Consider the area of backcountry and what your needs are to find the right water treatment for you. To cover all your bases my recommendation is for the best water filter you can. Plus pack a purification method for emergency backup.
Thank you for allowing Outdoors Informed with aiding you in your research. It’s our mission for you to spend less time inside and more out having fun in the backcountry.