How to Purify Water Backpacking

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Water is life, they say, and this rings true especially when you’re backpacking. Trying to carry all your water with you for a trip makes your pack heavy which wears down your body. This makes it critical to know how to purify water backpacking. In this guide we are going to dive into backpacking water purification, understanding the different methods, and how to choose the right one for your trip.

Key Takeaways

  • Learn how to purify water backpacking using filters, chemical treatments, and UV light purifiers.
  • Learn how to source water and how factors like group size, and the trip duration impact water filtration
  • Troubleshoot common water purification issues such as backflushing filters or ensuring correct dosage and contact time for chemicals.

How do you Purify Water Backpacking?

Purifying water in the backcountry is essential to ensure that it is safe for consumption, as untreated water may contain harmful bacteria, parasites, and other contaminants. Here are steps for purifying water in the backcountry.

Looking at a small stream

1. Find a Water Source

The first step for how to purify water backpacking is to find a water source. Choose a water source that appears to be clear and free of visible contaminants. Avoid stagnant water and opt for flowing streams or rivers when possible.

What to look for in a water source:

  • Look for flowing water, the best water is usually from a stream or river. Moving water is usually a great option because it is not as conducive to algae, bacteria, or microorganism growth.
  • Look for clear water. If not able to find clear water, look for calm water without a lot of sediment or silt. These sources could be a lake, a natural pond, a slow-moving stream.
  • Find a location that allows you to reach well away from the shore. Microorganisms tend to accumulate in higher concentrations near the shore.
  • Look for sources that have a relatively large amount of volume of water, in general a large volume of water may dilute the concentration of contaminants in the water.
  • Vegetation is not all bad, lush green moss is a good sign of clean water

Danger signs in a water source:

Knowing signs of sketchy water can help prevent the likelihood of contamination in your water. If you can choose another water source, do so. If not, be sure to thoroughly treat you water and possibly add a secondary treatment if really skeptical.

  • Be leery of water near meadows or pastures usually at lower elevations with livestock or near popular and well-established campsites.
  • Look for evidence of pack animal traffic or other domesticated animal activity.
  • Look for any excessive amounts of algae, whiteish foam, or brown scum, which can indicate algae blooms. Algae not typically harmful in some cases can be toxic like those that often occur at Isle of Royal National Park along the Greenstone Ridge Trail
  • Watch for dirty snow, especially if it is “yellow snow”. All jokes aside don’t assume that if the snow looks clean that it is safe, because bacteria and viruses can live in snow or ice for months.
  • Be leery of nonpathogen contamination such as bugs in soil, heavy metals, and chemical run off.
Gathering water with a 2L CNOC

2. Gather Water

The next step for how to purify water backpacking is know how to gather water without stirring up sediment. First, seek out the clearest possible water. Leaves, silt, and murky water do not necessarily pose a threat they just might make water a little harder to filter. To try and get clearer water even in murky water consider these strategies:

  • Gather from the surface: Use a pot in your cook set to scoop water from the surface or use a water reservoir like CNOC which is designed for easy scooping.
  • Use a prefilter. If you’re using a filter, its intake hose likely has one on the end. It keeps larger debris from clogging the internal filter element. Prefilters are even more essential for UV-treatment options and are often sold as an accessory item. No prefilter? Strain water through a bandanna before treating.

3. Choose a Water Purification Method

Lastly, when it comes to knowing how to purify water backpacking you have to choose a method that will work for you. Water purification methods can broadly be categorized into three types: filters, chemical treatments, and UV light purifiers.

Each of these methods has its strengths and limitations, and what works best for you depends on a variety of factors, from the quality of your water source to the size of your backpacking group.

Backpacking Water Filters

When it comes to the best backpacking water filters, there’s quite a variety to choose from. Some popular options include:

  • Pump filters, like the Katadyn Hiker Microfilter, which aim filter through a pump system.
  • Physical Filters, like LifeStraw or Sawyer Squeeze uses a range of filtration within a bottle or reservoir.
  • Gravity filter, which uses gravity to physically filter the water through to another reservoir.

However, it’s worth bearing in mind that despite a filters effectiveness in eliminating bacteria and impurities such as dirt, algae, and small organisms these filters and purifiers might not shield against viruses.

This is especially important to consider if you’re backpacking in areas where water may be contaminated with sewage or very turbid water. In such cases its effective to use a combination of treatments. Water purification chemical tablets or boiling water will offer secondary protection against suspicious water sources.

Filter TypePump FilterGravity FilterInline Filter
ExampleMSR Mini Works Ex FilterPlatypus GravityWorks Sawyer Squeeze
EffectiveProtozoa, bacteria, silt/sediment, some viruses. when <o.1 micronsProtozoa, bacteria, silt/sediment, some viruses. when <0.1 micronsProtozoa, bacteria, silt/sediment, some viruses. When <0.1 microns
Time~0.5 -1L per minute with force~0.5 -1L per minute with no effort~1L per minute with manual force
Weight~10 -15oz ~10 – 20oz ~2 – 5oz
Best ForSolo Groups Solo

Chemical Treatments

If you’re looking for a lightweight option or if you’re backpacking in regions where viruses are a concern, chemical treatments might be the way to go. These include options like Potable Aqua Iodine, Aquamira Water Treatment Drops, and Potable Aqua Chlorine Dioxide tablets.

Chlorine dioxide, a common chemical treatment, exhibits effectiveness against a broad spectrum of pathogens, such as bacteria, protozoa, and viruses. For instance, Potable Aqua Chlorine Dioxide tablets can protect against viruses and bacteria in as little as 30 minutes, although it does take a bit longer (four hours) to eliminate cryptosporidium.

One of the main advantages of chemical treatments is their extremely lightweight nature. Yet, chemical treatments are not without their share of disadvantages. For one, they can leave a slight pool water taste. They also require extended time up to 4 hours to kill all the germs.

These treatments are known for their reliability and durability, making them a popular choice among backpackers.

SteriPEN Ultra Water Purifier Video

Ultraviolet (UV) Light Purifiers

Finally, ultraviolet (UV) light purifiers, which utilize ultraviolet light, are a less used but also very effective purification option. These devices, like the Katadyn Steripen Ultra, work by using UV rays to eliminate microorganisms in water, such as bacteria, protozoa, and viruses, rendering the water safe for consumption.

The Katadyn Steripen Ultra is pretty straightforward to use. You simply insert it into a water bottle, invert the bottle, and gently agitate for about 90 seconds to purify approximately one liter of water.

The Steripen Ultra brings several advantages to the table:

  • Lightweight and compact
  • Easy to use
  • Cost-effective at approximately $0.01 per liter
  • Long lifespan, capable of purifying up to 8,000 liters or around 50 liters per charge

However, UV light purifiers do have their limitations. They:

  • rely on a USB-rechargeable lithium-ion battery, which can fail
  • are not effective in purifying turbid water
  • don’t filter out heavy metals or synthetic substances.


Boiling is a reliable method to kill most microorganisms, including bacteria and viruses. Bring the water to a rolling boil for at least one minute (or three minutes at higher altitudes). Only downside is if using for drinking water it will have to cool down prior to being able to drink.

Chemical MethodsBoilingIodineChlorine DioxideUltraviolet Light
EffectiveAll pathogensLimited by colder temp cloudiness of the water source. Not effective against crypto Kills majority of pathogens in 15-30 min. Crypto in 4 hoursAll Pathogens impacted by murky water
Time Time consuming and uses fuel~30 minutes~15 to 4 hours~90seconds per Liter
AftertasteNone, besides hot water Chemical tastingNone to very slight pool waterNone
Best ForCooking Warm Meals or liquidsSolo or secondary purification sourceSolo or group hikesSolo

Combination Methods

For added assurance, you can use a combination of methods. One of my favorite methods I often use especially if I have questionable water sourcing is to collect the water and chemically treat with chlorine dioxide and then use my Sawyer Squeeze to physically filter the water.

This is my method for more turbid water, if I have a source that looks less questionable and is from a running water source, I usually will opt to use the Sawyer Squeeze and may only use that for filtration.

Backflushing the Sawyer Squeeze filter

Maintaining and Caring for Your Backpacking Water Purification System

Upon selecting your water purification method, it is vital to maintain it properly for longevity and optimal performance. Regular cleaning, appropriate storage, and careful handling can all contribute to the longevity of your system.

Cleaning and Backflushing Filters

Regular cleaning and backflushing of your filter are necessary to preserve its flow rate and avoid clogs. When cleaning your filter and storing for long term it’s recommended to add a small cap of watered-down bleach solution and backflush that into the system prior to storage.

If wanting to clean for short term, then using clean water and backflushing that through will work well to unclog and clean the filter.

It’s important to note that different types of filters may have different cleaning methods. Always consult the manufacturer’s instructions before attempting any cleaning methods.

Storing Chemical Treatments and UV Purifiers

Storing chemical treatments necessitates:

  • Keeping them in their original containers with tightly secured lids
  • Placing them in a cool, dry spot away from direct sunlight
  • Routinely checking their expiry dates
  • Always storing the chemicals at the specified temperature to maintain their efficacy.

In the case of UV purifiers, here are some important storage tips:

  • Thoroughly dry the purifier before storage
  • Keep it in a dry place, protected from abrasive substances and extreme temperatures
  • Remove batteries or disconnect the power source to prevent potential damage during storage

Winter Care for Water Purification Systems

Providing winter care for your water purification system means safeguarding it against freezing temperatures. To do this, you can insulate any components of the filter. I recommend storing the system in a ziplock bag and keep it inside your sleeping bag or jacket to preserve warmth.

When storing a UV light purifier in cold weather, follow these steps:

  1. Remove the UV bulb and store it in a cool, dry location away from direct sunlight.
  2. The storage area should be well-insulated to protect against extreme temperatures.
  3. Using a protective case or container can help prevent damage to the purifier.
A covered water source

Primary Types of Waterborne Threats

Every water source on our planet has the potential to house any of these tiny microorganisms. Just ingesting a few of them can give you a bad case of the runs and other not-so-fun symptoms.

In water there are typically three main categories of organisms:

  1. Protozoa, like Cryptosporidium parvum and Giardia lamblia, come equipped with a tough outer shell that shields them from certain chemicals like Iodine.
  2. Bacteria, the midsize microorganisms, include familiar names like Escherichia coli (E. coli), Salmonella, and Campylobacter.
  3. Viruses, like Hepatitis A, rotavirus, and norovirus, are a bit of a headache to deal with. They’re smaller than protozoa and bacteria, so they slip through filters more easily.

Many illnesses attributed to bad water are actually caused by poor hygiene, so keep your hands clean. Pack hand sanitizer and use it often especially after each and every time you go to the bathroom. It’s also good practice to sanitize before food prep, before water duty, and after your hands have been in contact with a natural water source.

Frequently Asked Questions

What is the best way to purify water while backpacking?

A water filter like the Sawyer Squeeze that filter to 0.1-micron absolute filtration will remove 99.99% of bacteria such as salmonella, cholera, leptospirosis, and e. Coli, and removes 99. 99% of protozoa such as giardia and cryptosporidium. Chlorine dioxide is also highly effective though does not get rid of particulates.

Do I need a water purifier backpacking?

Yes, it’s advisable to use a water purifier while backpacking to prevent sickness from waterborne illness.

What are the benefits of using chemical treatments for water purification during backpacking?

Using chemical treatments for water purification during backpacking is beneficial because they are lightweight, effective against a wide range of pathogens, and do not require field maintenance. This makes them a convenient and reliable option for safe drinking water while hiking.

How does one properly maintain a backpacking water filter?

To properly maintain a backpacking water filter, ensure you regularly clean and backflush it with clean water or air to maintain the flow rate and prevent clogs.


Backpacking offers an exciting way to get out and into the wilderness, but the importance of having clean, safe drinking water cannot be overstated. While there are various methods available for water purification. The best method for you will depend on factors such as the quality of your water source, the weight and portability of the system, and the size of your group.

Regardless of the method you choose, proper maintenance and care, planning and having a second treatment option, can ensure you have access to clean and safe water throughout your trip.

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