How to Choose the Best Water Filter

survival water supply Nov 10, 2020
off grid water
Having pure drinking water is critical whether you live off the grid or not.   In fact, having an available water source will be a critical factor in choosing an off grid property. In some cases, you may be able to connect to city water. If you can drill a well then you have an independent water source. Whatever your availability of water may be, there is always the possibility of that water source becoming contaminated. This is why it is important to have a backup system in place. That back up system is as simple as having an alternative means of producing potable water. This is where choosing a water filter becomes important. But how do you choose the best water filter for your particular situation? 

With so many products on the market, how can you possibly know which one is the best water filter? How do you choose a water filter that suits your situation?  In this post, I will outline the primary factors involved in evaluating the different products on the market. Having this knowledge will help in choosing the best water filter or purifier that fits your particular needs. 

Factors for choosing the best water filter


-Frequency of use 

-Lifetime of the filtration element

-Ease of use

-Volume to be filtered

-Speed of operation

-Pre-filter element


-Ease of water transfer

-Filter versus purifier


-Back up method


This is a primary consideration in most things that we purchase.  If you shop around, you will find that water treatment methods vary significantly in price.  Consequently, you have to weigh price against all of the other factors involved. If you really want the best water filter, don’t go cheap. When it comes to pricing the different methods of water treatment, calculate the cost of price per liter of producing good quality water.  Ultimately, this is the best way to compare.  


Intermittent off grid ventures versus living off grid full time makes a huge difference in how you accomplish certain things.  This includes choosing the best water filter for your situation.  


How many liters of water can be filtered before the filtration element has to be replaced? This is usually not a consideration if you are only using a system as a temporary back up method or you intermittently venture into the backcountry.  However, if you filter water regularly, as I do, it becomes a major consideration. It directly affects the cost per liter of purified water. Frequency of use is directly related to the lifetime of the filtration element. 


If you ever find yourself in a situation where you have to treat water on a regular basis, you know all to well how the ease of use comes into play.  Sooner or later it becomes a deciding factor in using one product over another.  The ease of use was one of the primary factors that made me decide to change the water treatment methods I use at my off grid cabin.  


If water treatment is for only one person versus a family, obviously the product you choose will be different.  A group of people will need a product that will filter a larger volume in less time. If there is only one person, obviously the volume to be filtered will be much less. 


This goes along with the volume to be filtered. If you have to treat a large volume of water on a regular basis, you want a treatment method that will accomplish that in a shorter amount of time.  


Even pristine, clear, mountain stream water has a certain amount of floating sediment or particulate matter in the water. It does not take a lot of this type of material to clog a filter especially if you are treating water regularly.  A pre-filter element helps to solve that problem by taking out a lot of the sediment. Pre-filtering helps to maintain the flow rate of the filter or pump and decreases the frequency of cleaning the filter element. By removing sediment and particulate matter, it also improves the quality of chemical treatments.  


Every filter or purifier is going to require maintenance at some point.  The filter elements become clogged and need to be cleaned or replaced. How easily this is accomplished, especially in the field, is directly related to ease of use.  


Can you easily filter and purify water to be used later? For example, some treatment methods attach to the top of a water bottle.  You can only filter the water as you use it.  Consequently, it is not designed to filter large amounts of water and easily transfer that water in a separate container for transportation and use at a later time.  Additionally, the type of water container makes a difference.  I strongly lean toward using Nalgene water bottles. They are light weight, durable, and last for years.  Water bladders may be convenient.  However, they have a tendency to leak and they are notoriously difficult to keep clean.  


Know the difference. Not every water filter is also a purifier.

At the most basic level, water filtration removes impurities through the use of a physical barrier. Filtration systems are used to remove sediment and tiny particles such as bacteria and microbial cysts. In many cases, water filtration precedes purification.  

Water purification is often needed in order to ensure complete removal of biological contamination. Some organisms, especially viruses, are extremely small and a lot of filters will not remove them. (some will) Although not always true, water purification is often a chemical process. 

As a general rule, water filters will not remove viruses but water purifiers will.  With new technologies on the market, this is not a hard and fast rule. Some products listed as “filters” will remove viruses. Bottom line is that you have to read the product literature.  If virus removal is an important factor to you then purchase a suitable product. 

If you review a lot of products, you will note that water filters are discussed more frequently than water purifiers. But, you need to know the difference. If you truly want to be 100% safe, purchase equipment that filters and purifies water.


This is not a primary consideration if you are only treating water at home.  However, it is a different scenario if you are carrying something in a backpack or your vehicle. Make sure to purchase something that is easily portable if you want to take it with you.  


If there is one important lesson I’ve learned from living off the grid, it is “always have a back up”. The point is, no piece of equipment is going to be perfect. At some point in time something is going to fail. If you have a back up system in place, then the equipment failure or malfunction is simply a minor inconvenience.  No back up and you’re out of luck entirely. A back up water treatment system can be as simple as chemical additives that purify the water.  Most chemical treatment methods will add a taste to the water that some people consider unpalatable.  However, think of it as temporary.  This is far better than having no drinking water at all. 

Overview of the best water filters 

Chemical Water Treatment

Chemical water treatment is not really filtering.  But, it is worth including it here because it can be a life saver.  Many people think of this as the least expensive of all methods. However, compare prices carefully and always consider the end cost of price per liter of producing clean, drinkable water.  

Chemical treatment will eliminate bacteria, protozoa, and viruses.  The water does have to sit for some time, which is dependent on the type of product and the temperature. This method of purification is often used as a back up to other methods.



-Eliminates viruses

-Very light weight and small

-Easy to use


-Wait time for chemicals to take effect: 30 minutes to 4 hours depending on the water temperature and turbidity. Best practice is for the water to be at 60 degrees Fahrenheit (15.55 Degrees Celcius) .  Water at 40 degrees Fahrenheit (4.44 Deg. Celcius)  takes one hour exposure time.

-Chemicals used are either Chlorine based or Iodine based.  These will impart a taste to the water that some people find unpleasant.  

-Iodine products should be used with caution in pregnant women and people with thyroid problems. Check with your physician. 

-Iodine products are not effective against Cryptosporidium and only effective against 90% of Giardia cyst if the water temperature is 50 Degrees Fahrenheit or less.  

Chemical Water Treatment Products

Aquatabs Water purification HERE

Katadyn Micropur Water Purification Tablets HERE.

Aquamira Water Treatment Drops HERE.

Potable Aqua (Iodine treatment) HERE.

Potable Aqua (Chlorine Dioxide) HERE.



Boiling water as a means of purification is very effective and can easily be used as a back up method. Water should be kept at a roiling boil for at least one minute.  At altitudes greater than 6,500 feet (1981.2 meters) boil for at least three minutes. 


-Effective as a great back up method

-Turbidity does not reduce the effectiveness

-Easy to use


-Takes time to heat and cool water before you can drink it

-Water often tastes flat after boiling

-Requires the use of fuel which could be a precious resource in a survival situation

Straw filters

These devices allow you to drink water on demand directly from the source. Many advertisements for these straws show people bending over and drinking water directly from a stream.  However, its likely a better option to fill a small container and then drink from that.  


-Easy to use


-Purified water is quickly available

-Very light weight


-Water is only available when you are at a water source

-The only way to take extra water with you is to fill a container with contaminated water, which means that container would have to always be considered contaminated

-Field cleaning is required

-Not all products have replaceable filter elements


Military water purification straw HERE.

Lifestraw steel HERE.

Straw water filters @REI HERE.

Squeeze and bottle filters 

These types of filters are actually very similar. Squeeze filters work by attaching the filter to the top of the reservoir bag and then squeezing to produce pressure. Bottle filters fit inside the top of a water bottle and required suction provided as you drink or they operate similar to a coffee press. 


-Easy to use


-Light weight, compact, and portable

-Filter element is replaceable


-Water quantity is limited to the size of your water container

-Best used with clear water

-Turbid water greatly slows down the flow rate

-Field cleaning is required

-Adapters may be required to fit other water bottles


Ultralight purifier HERE.

Sawyer Squeeze HERE.

Katadyn Be Free HERE.

UV purifier

UV light is a fantastic way to purify water because it inactivates bacteria, protozoa, and viruses.  Besides the portable models, there are also models large enough to be used in a house.  It is best used with clear water because sediment and particulate matter impairs its effectiveness.  


-Easy to use

-Water is purified and drinkable in a short period of time.  

-There is no element to clean


-Cloudy, turbid water impairs the effectiveness

-May require a pre-filter

-A power source is required

-Portable models are only going to purify a small amount of water at a time.  Consequently, these are not good for large groups. 


Steripen HERE.

Katadyn Steripen HERE.

Gravity purifiers and filters

If you are filtering large amounts of water, a gravity filter is hard to beat as long as the filtration rate is high enough. Gravity systems can be a simple filter or a purifier. The great advantage of these systems is that you can set it up and walk away.  


-Gravity does the work for you

-Filters large amounts of water

-Filtration elements are replaceable.  


-Hanging a large bad of water can be difficult at times especially in the back country

-Filtration rate is often slower than a pump

-It can be difficult to fill the reservoir bag from a shallow stream or seep

-Depending on the model, field cleaning of the element is required.


Lifestaw mission HERE.

MSR gravity system HERE.

Platypus Gravity Works HERE.

Berkey Filters HERE.

Pump purifiers and filters

Pump filters and purifiers typically have an intake and output hose.  The intake is placed in the water source and usually has a pre-filter.  The output is then placed in a water container to receive the clean water.  


-Can easily be used in shallow streams and seeps

-Filtering is usually very fast

-Internal element is replaceable


-Pumping can be a chore at times, especially after a long day of hiking

-Field cleaning is required

-Pumps typically weighs more than other filtration equipment


MSR Guardian Purifier HERE.

Katadyn Hiker Pro HERE.

Seychelle Supreme Water Filter HERE.

What I Do: My Choice for Best Water Filter

My choice for the best water filter was based on my personal situation. I live in an off grid cabin on a full time basis. It sits on top of a ridge at 10,000 feet.  The access is somewhat limited. The road is a single lane shelf road wide enough for a passenger vehicle but not wide enough for a large truck of any kind. This prevents me from ever drilling a well.  Consequently, I have to haul water year round.  I have a 525 gallon cistern and a truck mounted 150 gallon water tank that is used to haul in stream water.  I disinfect the water that goes into the cistern by adding chlorine. This water is used for washing dishes and taking showers. For drinking water, I use a gravity fed Lifestraw Mission, which hangs in my shower. It is a 12 liter system and is great for three people.  

As an additional water filtration system, I have a table top bucket system. It is made of two 5 gallon food grade buckets and two Berkey water filtration elements. It filters at a much slower rate but serves as a great back up and an additional source of purified water.

This is the Lifestraw Mission that hangs in my shower. 

I put two Berkey Filters inside 5 gallon food grade buckets to make a simple gravity fed system.


I also have a Sawyer Squeeze that is part of an emergency kit that stays in my truck.

Additionally, I have a Katadyn filter that is basically the back up for the back up. One of the most important lessons I’ve learned about living off the grid is always have a back up.

There is a lot of information out there regarding water filters. As you can see, there is no one right answer for anyone.  You just have to pick something that is suitable for your particular situation.  

Additional Posts of Interest
The Ten Essentials Needed for Survival
How to Maintain a Safe Water Supply


Go off grid and live well, 


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