How to Choose a Water Filter for Backpacking

How to Choose a Water Filter for Backpacking

When you want to choose a water filter for hiking or camping it can be a difficult choice because of the variety of options available. We all know we need water while hiking or camping, but carrying all the water you need for a hike or camping trip can be exhausting.

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Hikers and campers usually count on finding water from streams, lakes, snow run-off, or other water sources in the natural world. Unfortunately, that bubbling mountain stream or clear lake water may not be safe to drink without treatment. Bacteria, protozoa, and other contaminants can be present in the water, even when it looks pristine and can cause a multitude of intestinal and other woes.

Any time your water is from an untreated source, you should treat it before using it for drinking, cook, or even brush your teeth. An easy solution is to carry a water treatment system with you that can protect you from pathogens in the water that are harmful to your body. There are two kinds of portable water treatment systems that are readily available and easy to use. You can choose a water filter or a water purifier, or a combination of both, based on your needs.

Here’s a look at some of the differences between water filters and purifiers, and the pros and cons of each.

First, you have to decide if you need a water filter or a water purifier.

What’s the Difference Between a Filter and a Purifier?

A water filter uses a physical element to remove the bacteria and protozoa from the water. If you are hiking or camping in the US, bacteria, and protozoa are the two main hazards you will encounter in natural waters. However, most water filters will not filter out viruses. Viruses are too small and will pass through the pores of most filters. Viruses are most worrisome outside the US.

A water purifier is approved to neutralize bacteria and protozoa as well as viruses found in natural water. There are two main types of water purifiers:

  • chemical purifiers
  • ultraviolet light purifiers.

UV light purifiers actually use an UV light element. The UV light will neutralize the contaminants in the water with no harm to you. Chemical purifiers use a chemical, usually chlorine or iodine, in the form of drops or tablets, which are stirred into the water.


How to Choose a Water Filter or Water Purifier

The first thing to consider is location. Where is your planned hiking or camping trip? If you’re in the United States, protozoa and bacteria will be your main threat. Water filters are a preferred and safe choice for hiking and camping within the US.

If you are traveling abroad, a water purifier is the safer choice. These can be used anywhere in the world and are ideal where waterborne viruses are a concern. Purifiers are necessary where viruses are present or where you find a lot of animal or human activity and waste.

Other factors include the weight and size of the filter or purifier, its ease of use, the difficulty of maintaining the purifier on the trail, the expense of the product, and the quantity of water you will need to purify.

If you’re filtering water just for yourself or for a short hike, you might not need something that can treat a large amount of water. However, if you’re filtering water for a group camp, or if you will require a lot of water for cooking, you will need to consider that factor when choosing a water filter or purifier.

Each person or group will need to consider each of these factors and balance what is needed the most. No one product will be the perfect answer for everyone.

Here’s a look at each category of filters and purifiers and the pros and cons of each. First, we’ll explore the choices of filters.

Pump Filters

Pump filters work by having an intake hose placed into the water source and another piece, or hose that attaches to the collection container for your filtered water.

Katadyn Vario Multi Flow Water MicrofilterEssentially, you will hand pump the water through the filter. The dirty water gets pumped through the hose from the water source, through the filter and into your water bottle or another container. Pump filters are easy to use and to maintain while out in the field.

It’s easy to replace the cartridges and to backflush the pump if it becomes clogged. You can also choose the quantity of water you want to filter. You just keep pumping dirty water until you have enough.

However, pump filters are heavier and bulkier than some other types of portable water treatment, making them somewhat cumbersome to carry. Also, if you must treat water for a large group, it can be tiring and time-consuming to pump a large quantity of water.

Gravity Filters

LifeStraw Flex Advanced Water Filter with Gravity BagGravity filters, as you might expect, use gravity instead of a pump to force water through the filter. A gravity filter is made up of a two-bag system. One bag is filled with dirty water and positioned above the second bag, connected by a hose that flows through the filter. Water is pulled through the filter by gravity into the clean lower bag.

One advantage of a gravity filter is that gravity does all the work for you. It’s easy to use. You fill the bag, wait for gravity to work, and you have clean water. It is easy to filter large quantities of water with a gravity filter, making it great for groups of campers and for treating water for cooking. The filters are easy to replace and easy to maintain on the trail.

One difficulty with gravity filters is that it is necessary to have a sturdy place to hang the water bags. Another problem is, unlike a pump filter where you can pump water from even small sources of water, gravity filters require you to fill a bag of water from a relatively large source of water, preferably without putting the water bag into the water. This can be a challenge in some settings.

Drink-Through Filters and Purifiers

LifeStraw Personal Water FilterDrink through filters and purifiers include a wide range of different products. Essentially, you fill a water bottle or bag with dirty water and then squeeze it through a filter – straight into your mouth. It’s a drink-through filter, just as it sounds.

There are several options in this category. One is a bottle or bag with a filter in the cap. You simply squeeze water through the filter. Another option is a large “straw” with a filter that can go directly into the water source or a filter with a hose that can go straight into a water source.

Drink through filters are easy to use, compact and lightweight, making them easy to carry. They are an excellent option for activities like day hiking, mountain biking, and trail running. Another positive is that they work quickly. You can start hydrating as soon as you find a source of water.

On the downside, drink-through filters don’t easily filter large quantities of water. However, it is possible to combine them inline with a system of bags to create a gravity filter if a more substantial amount of treated water is needed.

Water Purifiers

There are two main categories of water purifiers to choose from: UV (ultraviolet) light purifiers and chemical purifiers. Water purifiers can neutralize bacteria, protozoa, and even viruses. That’s one of the major advantages of using a purifier: they are effective in neutralizing viruses. That’s something most water filters can’t do.

UV Light Purifiers

SteriPen Adventurer OptiA UV light purifier is a stick-like device containing a UV light element. It is placed in a water bottle and stirred. The UV light will neutralize contaminants in the water – bacteria, protozoa, and viruses. UV light purifiers are also lightweight and easy to use.

Unfortunately, UV light purifiers can generally purify only a small amount of water, about the amount of water in a water bottle. The UV element does not need to be replaced or cleaned, but it does require a battery. You will need to carry an extra battery or two with you on the trail.

Another complication of using a UV purifier is that they don’t work well with dirty water or water filled with silt. The dirt in the water may prevent you from being able to purify the water. The solution is to use a pre-filter. The UV purifier won’t remove the dirt, but the filter will. Filter the water first, then purify it with the UV stick for a complete purifying system.

Chemical Purifiers

Potable Aqua Water Purification TabletsFor water purification, your other option is to treat the water chemically. The two main chemical treatments use either chlorine or iodine as a base. Chemical treatments are small, lightweight, inexpensive, and very easy to use. You drop a tablet or a few drops of the chemical into the untreated water, stir, and wait. They are a great back up option to carry even if you have another form of water treatment with you.

The downside of using a chemical treatment as your main form of water purification is the time needed to purify the water. Depending on the chemical treatment used, you will have to wait at least 30 minutes and up to 4 hours for the water to become potable. Environmental conditions are also a factor. Water temperature can affect the time it takes for water to be treated and become drinkable.

Iodine purifiers also leave a metallic taste in the water. You can add additional chemicals to treat the taste, but you will have to carry them with you.

A significant drawback to using either chemical treatment to neutralize protozoa is that neither chemical works to neutralize cryptosporidium parasites. This nasty little bug is one of the most common causes of waterborne illness in the US Again, using a filter than is approved to remove these protozoa along with a chemical treatment may be the complete system for protecting yourself from illness.

These chemicals are also not recommended for pregnant women or people with thyroid conditions.

Boiling Water

Camping Cookware Mess Kit Backpacking GearA final option is good old-fashioned boiling. Boiling water works as a treatment for most contaminants. Water must be brought to a full rolling boil for a full minute or a full 3 minutes if you’re over 6500 feet in elevation to eliminate contaminants.

While you don’t need to purchase additional supplies, you will have to carry extra fuel and something heavy to boil the water in. You also need to factor in the additional time required to bring the water to a boil and then wait for it to cool down to drink it.


Consider your location, possible contaminants, length of your trip, size of your group, and other factors while making your decision. These are some great options so you can choose what will work best for you.

Good luck out there!