How Do Camping Water Filters Work? (Explained)

When you don’t really understand how the water filtration process works, it can be tough to figure out the best kind of filter to buy for your next camping trip. So, before you pick your next filter, it’s a good idea to learn how camping water filters actually work.

Camping water filters work by removing sediments and impurities that come from dirt, plant life, and waterborne contaminants like protozoan cysts and bacteria. Most camping water filters are similar in comparison, but all are designed to allow you to drink dirty water and not get sick.

The type of filter you need depends largely on how many people you’re supplying water for. But whatever your needs, there are a variety of options to choose from, and we go through all of the different types and how they work below.

Different Types Of Camping Water Filters

There are three main types of camping filters, but the assortments available to choose from are endless. Don’t confuse water filters with water purifiers, which are not discussed in this article. Often used interchangeably but not correctly, water purifiers also filter out viruses, whereas water filters do not.

1. Pump Filters

Pump filters use the same concept as a siphon hose or sump pump. You put one end of the hose into your water source and begin manually pumping the water. The pump siphons the water into an intake hose, through your water filter, and into your holding reservoir on the other end of the filter.

They are very easy to use and maintain. You can change the filter, or backflush (force water through in the opposite direction) the filter while in the field to push out the buildup of gunk, debris and contaminants. It’s also relatively easy to pull from a shallow source of water.

The downside to pump filters is that they are generally heavier and bulkier than other varieties. They are more difficult to use for larger groups because of the labor involved with the amount of pumping necessary to produce mass quantities of water. 


  • Easy to use and maintain
  • Easy to swap out filters or backflush it


  • Bulkier than other options
  • Require more work to use

2. Gravity Filters

Gravity filters use a two-bag gravity system. One bag acts as a holding tank for your dirty water. Hang it up somewhere and gravity naturally drains the bag through a tube that leads to your filter. After passing through the water filter, it will pool in your storage bag, which is suitable for drinking.  

The advantage of a gravity filter is that there is no labor involved. Gravity does all the work for you. All you have to do is fill the bag, hang it, and wait for it to filter through. This works particularly well for larger groups when mass quantities of water are necessary to supply multiple people. 

Gravity filters are also easy to maintain, and the filters are easy to replace. They come in a variety of assortments and sizes to fit your needs.

The disadvantage is that you need a larger body of water to adequately fill the bag. You also need to ensure you have access to a spot to hang the bag, which may be challenging in certain terrains. Depending on how much water you are filtering, it could also take a bit of time.


  • No input required
  • Useful for producing mass quantities of clean water


  • Takes time to work
  • Need to find a spot to hang the bag

3. Drink-Through Filters

Drink through filters (sometimes called personal water filters, inline filters, or survival filters) are probably the most common and can be readily found at almost any sporting goods store or online. Virtually all drink-through filters are designed for individual use.

There are a wide range of products to choose from and all of them allow you to drink directly from the filter like a straw. By design, they attach to squeeze pouches, water bottles, and inline hydration packs or gravity filters.

Squeeze Filter

Squeeze filters attach directly to a pouch of dirty water. Simply squeeze the pouch to force the dirty water through the filter right into your mouth. They can sometimes double as straw filters or gravity filters. They are convenient for day outings or hiking trips because they are easy to pack. The capacity is limited to the size of your pouch, but there are different sizes available.

Straw Filters

Straw filters only allow you to drink directly from a water source but don’t allow you to store water in any way. These are good for emergency situations, but you always have to be near a water source to use them. Some straw filters, however, can act as inline filters also (see below). Be sure to do your homework and understand what you’re purchasing before you take it out into the field.

Bottle Water Filters

Some bottle filters come with their own water bottle, while others come designed to fit standard water bottles. They are essentially the same as a squeeze filter, but they just come with a bottle instead of a pouch. For bottle filters and squeeze filters, study the durability of the reservoir. If you have to continually buy replacements, consider that this means added expense over time.  

Inline Filter

Inline water filters are usually designed to attach to a hydration pack or other reservoir system like a gravity filter. Many bottle filters and straw filters can double as inline filters also. You can fill your hydration pack with dirty water, run it through an inline filter, and into your mouth.


  • Versatile and easy to use
  • Lightweight and compact
  • Fast and convenient


  • Can’t filter mass quantities of water at one time
  • Require more maintenance/backflushing
  • Some can only be used at a water source (no storage)

How To Choose A Camping Water Filter

There are lots of things to consider when choosing the best camping water filter for your needs. In many instances, you may even decide to buy more than one type depending on what you plan to do.

Quality And Quantity

The first thing most of us think about is, of course, the price. You can pay a lot of money for a camping water filter, but do you really need to? In most cases, you can get a good quality filter for under $50. Before you buy, make sure it fulfills your needs. A little bit of research goes a long way here.

The amount of water that you will need to filter is probably the most important consideration. If you are just filtering water for yourself, then a drink-through filter or pump filter is probably best. It’s really a matter of preference as to which one is better. 

If you need larger quantities of water to serve many people, then you would need to decide between a pump filter or a gravity filter. Both are capable of providing enough water, but gravity filters may be easier to use and you can let it do all the work.

Weight, Ease, And Convenience

The weight and size are important factors depending on how much room you have to pack everything. Is your filter a standalone device, or does it have lots of additional parts like squeeze pouches, water bags, or backflush syringes that you’ll also need to pack?

Take a look at how easy the filter is to use. Some pumps have a lot of attachments that can be confusing. You likely want something that’s quick, easy, and convenient. Especially if you are new to water filters, the last thing you want is some complex mechanism to figure out while you’re trying to relax or have fun!

Maintenance And Durability

Filter maintenance is another important consideration. You need to have the ability to clean and maintain your filter while out in the wilderness. Make sure the pump you choose not only has this option available, but that it is also relatively simple and easy to perform. 

Analyze the durability of the pump you are considering. Make sure it is made of quality, durable materials that will last. If it looks flimsy, chances are it is. Take a look at how often bottles and pouches will need to be replaced, as well as the filters themselves. Also make sure that any additional components are easy to get a hold of.

Knowing how much water you can get from one filter is a key consideration in understanding your maintenance needs. The number of gallons one filter produces directly impacts your maintenance costs. So, it makes sense to find the most bang for your buck. 

How Do Portable Water Filters Work?

Portable water filters work differently depending on the type of process they use. Most camping filters will use a mechanical filter that utilizes absorption filtration such as a micro-filter, carbon filter, hollow fiber membrane, or a combination of these methods. 

These permeable barriers cause microorganisms to adhere to the surface of an absorbent membrane in order to capture waterborne contaminants. Many portable water filters use a combination of mechanisms that act as microscopic strainers in order to achieve 99.9% efficacy.

What Portable Water Filters Don’t Do

Portable water filters cannot remove waterborne viruses. Waterborne viruses include things like Hepatitis A and E, E. coli, Salmonella, Cholera, and other viruses spread through urine and feces. Many waterborne viruses result in gastroenteritis, which can cause abdominal cramping, diarrhea, vomiting, and fever.

While this is less common in the US, it’s still worth considering and may warrant investing in a water purifier or other water treatment option

How Well Do Camping Water Filters Work?

Camping water filters work well at removing waterborne bacteria and protozoa. With today’s technology, reputable camping water filters are good at safely filtering dirty water and making it drinkable without making you sick. However, most water filters will not remove viruses, while purifiers do.

Drinking unsafe water can lead to a lot of pain and suffering, and even death. Knowing some of the technical stuff, as boring and mind-boggling as it is, could be the difference between a successful expedition and a disaster. Most, if not all, of the filters on the market claim to remove 99.9% of contaminants, bacteria, and protozoa, but verifying that information can take a little work.

Meeting EPA Guidelines

It’s important to know that the EPA sets the standards for water filtration, but they do not enforce those standards. It’s really up to you to make sure that you’re buying an adequate filter. 

Almost all filters claim to meet or exceed EPA standards. Some are even certified to meet those standards. You should research thoroughly to ensure that the filters do indeed meet the claims they’re making. Many of the product websites contain sufficient enough testing data to show the efficiency of their filters.

Understanding Technical Efficiency 

All water filters have what is known as a micron rating. This rating determines the ability of a filter to sift contaminants by measuring the distance between the filter media. Most of the filters on the market today profess to filter anything larger than 0.1 to 0.2 microns. This means the mesh of the filtering media is 1/10,000 millimeter apart.

To wrap your mind around what that means, 1 micron is 1/1000 mm in diameter. A micron size of 5 would be visible to the naked eye, whereas a micron size of 1 would need a microscope. A 0.5 micron is able to remove protozoan cysts like Cryptosporidium and Giardia. So, theoretically, the 0.1 micron is able to filter 99.9% of the bacteria and protozoa that would be detrimental to your health.

Tips For Maintaining Filter Efficiency

It’s important to carefully read and follow any directions that come with your camping water filter to ensure that you are using it properly. Each filter will have its own set of steps for introducing water to the device. Failure to follow directions adequately could lead to the filter not working effectively. 

If you’re using a gravity filter, be sure to clearly label “dirty water” and “clean water” bags so you don’t cross-contaminate your water supply. Be sure to give your bags a good clean and rinse following your adventure to make sure they work well on your next trip. 

If you only have access to a muddy water source, then pre-filter first to remove as much of the sediment as possible. You can do this with a bucket of pebbles or rocks, or even a t-shirt or bandanna. This will prolong the life of your filter, as well as the need for field maintenance or backflushes. 

When camping in freezing temperatures, you have to make sure your filter doesn’t freeze. The expanding and contracting of the ice destroys your filtering media. Once the media is enlarged by the expansion of freezing ice, it’s less capable of filtering smaller microorganisms, and therefore is no longer safe. To prevent your water filter from freezing, you can store it in your sleeping bag at night. 

How Long Do Portable Water Filters Last?

How long your portable water filter lasts is really dependent on the specific water filter you purchase. Some advertise 100 gallons, while others advertise 100,000 gallons. Still, even others claim lifetime use, but to make the most of your water filter you should clean and maintain it regularly.

These numbers are likely overinflated as is the case with most advertising. It’s not uncommon to buy an item that falls short of its claim to fame. In perfect conditions, they may work to these numbers. But when do we ever get perfect conditions when embracing Mother Nature?

Larger May Last Longer

Larger filters will have a tendency to last longer than smaller ones simply based on their size alone. There is more filtering media involved, and anytime you have more of something, it usually lasts longer.

Other factors include the water source you’re using. Continually filtering muddy water will shorten the life span of your filter. How well you clean and maintain your filter after each use is also an important consideration.  The more TLC you give your filter, obviously, the longer it will last.

How Much You Use It

Also, keep in mind the age of your filter. Regardless of how many gallons you’ve siphoned through your filter, it will simply become aged with time.  If you don’t use it that often, then it shouldn’t matter, but if you’re a frequent flyer, then it will become brittle faster with routine use.  

At the end of the day, you’ll likely need to replace the filter because of physical damage rather than exceeding its water limit. It’s always a good idea to have an extra one on hand anyway.

Final Thoughts

Portable camping water filters work by removing bacteria and protozoa from dirty water and making it safe for you to drink. Water filters work in different ways and come in various shapes and sizes. You can find ones that use gravity filtration, and others that require a pump to work.