water filters

Best water filters for survival use

by survival expert James Mandeville

water filters reader rating=4.5
July 2016.

Portable water filters that also purify water

Personal water filters
Pre-Mac filter2019 update: Please note that Pre-Mac International Ltd has been dissolved and their filters are no longer available except, if you are lucky, you may pick one up through government surplus suppliers.

The Pre–Mac Personal Water Purifier Model (PWP) has been specifically designed to exacting standards and produces safe drinking water from sources with high levels of bacterial, viral and parasitic contamination. It is designed to fit to a standard issue NATO water bottle. The Model PWP will also remove organic matter that exists in most natural water sources, improving taste, smell and appearance of the water. The Model PWP provides all the treatment necessary to produce water that is safe and pleasant to drink. Compact and easy to use, it will purify 1,000 litres (264 US gallons) of water before replacement is necessary.

travel-well-ranger filter
(Above photo shows military version left and "The Ranger", the civilian version right).

The Mobile Water Purifier (MWP)
Mobile Water PurifierThe MWP is valuable where weight and size of equipment is important and it can realistically provide daily support for 1–4 persons at normal consumption rates. The MWP will provide 1 litre (0.26 US gallons) of purified water in 2.5 minutes and has a nominal capacity of around 200 litres (53 US gallons) with absolute safety. These purifiers use replaceable cartridges, which should be replaced once the unit becomes hard to pump. Designed to fit to a standard NATO water bottle.

The Survival Water Purifier
(SWP) is smaller and designed to meet specific Survival Water Purifierrequirements for treatment of water in emergency or survival conditions. It will provide an emergency supply of safe drinking water for one or two persons from contaminated sources at normal consumption rates. The small size and weight of this purifier makes it an excellent addition to any survival pack or personal survival kit. In operation, it works in exactly the same way as the Mobile Water Purifier. The SWP is convenient to use and will not blockMWP filter due to its high filtration capability and in–built pump. The rated nominal capacity of The SWP is 50 litres (13 US gallons), but needs only be discarded when the unit becomes hard to pump. It has a flow rate of 0.2 litres (0.05 US gallons) per minute. Unit Weight: 60 g (2.1 ounces). The water is not immediately ready for drinking, as the secondary disinfection continues for at least 3 minutes.

MSR – SweetWater Purifier System

MSR – SweetWater Purifier System
Collect water that is as clean as possible. After pumping through the SweetWater microfilter, add 5 drops of SweetWater purifier solution per litre of water. Mix for at least 10 seconds. Wait 5 minutes before drinking the water. Lever–action pump handle and dual pump action makes this filter fast to use. This filter worked well in our field tests but the drawback is carrying a bottle of purifier along with you. The purifier comes with the warning that it causes irreversible eye damage if you splash it in your eyes.

Inactivates 99.99% of waterborne viruses, eliminates over 99.9999% of all waterborne bacteria and 99.9% of common protozoan parasites, such as Giardia and Cryptosporidium, as well as particulates and chemicals/toxins.

Activated carbon core helps eliminate taste and odours.

Iodine–free: Inactivates viruses without bad–tasting iodine.

Compact: Handle folds flat when not in use for easy packing and storage.

Weight 397 g (14 ounces)
Width 5 cm (2 inches)
Length 19 cm (7.5 inches)
Filter media Silica Depth Plus Sodium Hypochlorite
Filter pore size 0.2 microns
Flow 1 litre / minute (1.8 pints/minute)
Flow (strokes per litre) 75
Cartridge life 750 litres 198 US gallons)
Cannot be cleaned or maintained in the field.
Has water bottle adapter.
Has cartridge replacement indicator.


Katadyn Hiker Pro Water Filter

Katadyn Hiker Pro
Hard to clog and easily field serviceable, this durable filter eliminates Giardia, Cryptosporidium and all bacteria and micro–organisms. This Katadyn water filter also comes with a field replacement kit for extended trips. The filter cartridge is tested at 750 litres (198 US gallons). While it can probably go longer if needed, Katadyn recommends replacing the Katadyn Hiker Pro water filter cartridge after 750 litres 198 US gallons.

Filter Material
Glass fibre with activated carbon Output: 1 litre/minute (1.8 pints/minute). Field–Cleanable. Weight: 312 g (11 oz). Manufacturer Warranty: 1 year.

Katadyn Hiker
The Katadyn Hiker Pro water filter physically removes particles, protozoa and bacteria down to 0.3 microns in size, including Giardia, salmonella, Cryptosporidium and others. I've also used it to suck water out of a slime–filled muddy pond. It can scavenge for water in very shallow puddles. The fact that you only need a minimal amount of water for this filter to work is a huge benefit over gravity filters and tablets. I always carry Katadyn Micropur Purification Tablets as an emergency back up, but I've never had to use them in conjunction with this filter.

Maintenance on the Katadyn Hiker Pro water filter is pretty straight forward. Important to read the instructions to get the best results. For storage after each trip you should do the following:

1. Fill a 1 litre (1.8 pints) container with tap water and add 2 tablets of Micropur Forte (or a few drops of ordinary household bleach).

2. Place pre–filter into solution.

3. Pump entire amount of solution through unit (into sink or container).

4. Remove pre–filter from the solution and continue pumping another 5 to 10 strokes to remove remaining water from the pump body and hoses.

5. Remove cartridge and allow to dry.

6. Wrap hoses around body and store in carry bag.

7. To clean filter protector, simply rinse it in the water.
Katadyn Hiker diagram

The Military Specification MIOX Purifier "Pen"
This is a highly recommended piece of kit as a back up emergency water treatment unit. A civilian version can be bought with a very similar specification. It is small, light about the size of a large marker pen. Prototypes of the MSR MIOX Purifier performed flawlessly during Operation Enduring Freedom in Afghanistan and provided safe drinking water to Iraqi citizens during the war in Iraq. Illustrated below is the military version.
MSR MIOX Purifier Military
Downside considerations:
  • It's electrical. Electrical equipment in a combat or an extreme survival situation is not always reliable.

  • The MIOX uses CR123A batteries. These are not always readily available in some countries and are also fairly expensive; however, they have a shelf life of 7 to 10 years.

  • The MIOX also takes a long time to treat water completely. To kill all viruses you are looking at around 4–5 hours. The upside is that it kills the most common health–threatening bacteria in less than half an hour.

  • Because the MIOX is not a filter, you may still have some floaters in your water and end up drinking a cocktail of dead pathogens.

  • Some field tests I tried, failed, because the unit constantly gave a low salt warning however much salt was added and however much the unit was shaken. MIOX say they have now fixed this fault in new units.

  • Although MIOX claim to the contrary, there is an unpleasant aftertaste in the water; it depends upon one's taste buds how tolerable or not one thinks this is — if you are dying of thirst it is not really an issue.
Modelled after today's hi–tech MIOX city water treatment system, the MIOXMSR MIOX Purifier in use Purifier "Pen" works by creating a brine solution out of untreated fresh water and ordinary salt, then it passes a small electrical charge through the solution, which results in a powerful dose of 'mixed oxidants,' thus the name MIOX. The solution is then poured into untreated water, inactivating viruses bacteria, Giardia and Cryptosporidium (which even iodine does not totally deal with), leaving you with safe, purified water. Illustrated photo, right is the military version.

  • No pumping required: Just add water, shake and press a button.

  • Purifies water without iodine: No health risk or unpleasant iodine taste.

  • Great for large volumes of water: Perfect for groups or extended trips.

  • Ultra–light and compact: Fits in your pocket to go anywhere.

  • Reliable purification Inactivates all viruses, bacteria, Giardia and Cryptosporidium.

  • Maintenance–Free: Simply replace batteries and salt.

  • Built–In Safety: Safety indicator strips verify performance in 'worst–case situations'.

Dwell times
Viruses, bacteria: 15 min.
Giardia: 30 min.
Cryptosporidium: 4 hrs.

Kit Includes
MIOX® Purifier, salt, batteries, safety–indicator strips, instruction booklet, quick–reference card and storage sack.

The MIOX Purifier occupies only 14 per cent of the space required by a typical portable water treatment filter and is one quarter the weight. Each dose will treat anywhere from 0.5 litres (0.13 US gallons) up to 3.8 litres (1.0 US gallon) of water.

The device operates by converting a brine (salt) solution to a mixed–oxidant solution via electrolysis. Each purifier utilizes two 3V Lithium camera batteries (included), common salt and a tiny electrolytic cell. The purifier will treat approximately 200 litres (53 US gallons) of water on one set of batteries. The purifier can be used over and over, making water treatment an inexpensive procedure after the initial purchase. An important feature of using simple salt as the disinfectant source is that salt has an infinite shelf life, so the purifier will still function even if stored without use for a long period of time.

The disinfectant will inactivate chemical and biological warfare agents. Illustrated below is the retail version.

MSR MIOX Purifier Retail
The purifier has passed the EPA (United States Environmental Protection Agency) Guide Standard and Protocol for microbiological purifiers, achieving more than 10 times the level of inactivation required, even in the EPA's 'worst–case' water.

Dugway Proving Ground in Utah, a U.S. Government laboratory specializing in chemical and biological warfare agents, has been testing MIOX mixed–oxidant solution since the year 2000. Findings show high efficacy against all agents, including Anthrax spores. Mixed oxidants achieved up to 99.99 per cent inactivation of the spore, depending on the dose and contact time. The mixed–oxidant solution also effectively destroyed the bacteria associated with Plague and the viruses associated with smallpox and polio. Mixed oxidants were also extremely effective against the nerve agents Soman (GD) and V–Agent (VX) and the blister agent Lewisite (L).

Survival–Pure In–line System

Survival–Pure In–line System

Survival–Pure In–line System in use
Survival–Pure's in–line purification system is for use with a water bladder or camel pack carried in a backpack or it may be used as an independent filter. A black outer case contains the purification system, which is simple to fit to any water bladder via barb fittings. The filter contains a post–purification scrubbing system with 2.0–micron filtration and uses "tortuous path technology" for maximum effectiveness. The filter may be used as a gravity–fed filter as shown in the photo above or fitted to a water bladder carried in a backpack; the drinking water is sucked directly through the filter. The gravity fed system has the advantage it can be used to fill a mess tin and therefore the water can be shared around with others.

MSR make a similar system
MSR filter
The AutoFlow Gravity Microfilter combines water filtration, storage and collection into a single, lightweight and pump–free system that filters up to 1.75 litres (3 pints)per minute. Four litre (7 pints) reservoirs allow you to filter large quantities at once making it perfect for groups, while quick and easy tool–free cleanings maintain high flow rates on extended expeditions.

Fast: Filters more than 1.75 litres (3 pints) per minute.
Lightweight: Weighs only 229 g(10.5 ounces)
Field–maintainable: Can be cleaned repeatedly without disassembly for flow recovery.
Adaptable: Filters directly into almost any bottle or reservoir using the included Universal Bottle Adapter.

Effective against bacteria, viruses and particulate but not effective against chemicals/toxins. In our field tests, we found it performed as claimed. Possibly, best suited for source water with only light contamination, such as, running stream water. Water heavy with debris was still filtered but this was slower than some of the other filters discussed in this section.

LifeSaver® Bottle

LifeSaver® Bottle

The LifeSaver Bottle is water purification device that can remove debris, bacteria and viruses from water. It is based on a unique membrane filtration system. With 15–nanometre diameter filtration, it effectively creates fresh water instantly and safely but cannot filter salt water. The LifeSaver Bottle provides a water scavenging capability, which is useful in a disaster zone, combat or other extreme survival situation. In the author's view, this is the best portable filtration system available to date.

Initial flow rate 2.5 litres (4.4 pints)/min@0.25 Bar

Cartridge service rating 4–6000 litres (1056–1585 US gallons)

Bacteria retention >99.999995%

Virus retention >99.999%

Chemical reduction – Activated carbon reduces chemical residues, including pesticides, endocrine disrupting compounds, medical residues and heavy metals.

Bottle storage capacity 750ml (1.6 pints)

LifeSaver© Bottle in use
LifeSaver Hydrocarry UF
Designed specifically for the foot soldier, LifeSaver Hydrocarry UF is the world's first ultra filtration hydration pack.

It produces filtered sterile drinking water quickly and easily from any local source of water. It also incorporates unique Chillwick™ technology, which, by using the principles of evaporation, draws heat from the water in the storage bladder and drinking tube, delivering cooler water to the soldier. Available to militaries around the world, it filled a critical gap in the current military hydration pack market.

The integrated Dualpump™ has two functions. As well as pressurizing the system to pass water through the filtration process, it also offers the soldier the significant tactical advantage of being able to fill the Hydrocarry UF from any water source, without having to remove it from his/her back. This speeds up the time taken in obtaining water and reduces the vulnerability of the soldier in combat.

Surviva–Pure Canteen
Surviva–Pure Canteen
Although not technically a drinking straw, the Web–tex Surviva–Pure Canteen is a useful portable purification system made to the same high military specification as all the Surviva–Pure products. The canteen is filled with contaminated water, which passes through a filtration and purifying system that forms the screw cap. The disadvantage of this system is that you are carrying around a water canteen filled with contaminated water and the canteen has to be cleaned out periodically and scalded with boiling water. Great care has to be taken when the canteen has been dipped into contaminated water not to get any of the water near the drinking mouthpiece. The screw cap does not fit a standard NATO water bottle, which is a great shame.

Surviva–Pure Canteen in use
Instantly removes: Chemicals, herbicides, pesticides, purification chemicals and sediments and trace metals.

Proven to remove: water–borne disease, causatives, Cryptosporidium, Giardia, E–coli, viral disease–causing contaminants and anthrax. Capacity 850ml (1.5 pints). Lifespan of filters: up to 1,600 litres (423 US gallons).


Purifying Straws

Water purifying straws, at the time of writing, use similar basic technologies – chemical purification, a filter system or a combination of both. It is recommended that straws using an iodine–type purification process only be used for about 2 weeks as the iodine becomes harmful to the body with prolonged use. These straws are ideal for emergencies but cannot safely be used on long–term basis. Straws cannot be used in chemically contaminated water, brackish water or seawater and they tend to clog up in water containing large quantities of debris, at which point, it becomes difficult to suck water through them. The main advantages of purification straws are that the water can be drunk immediately and they are light and relatively small in size. They should all be regarded as extreme survival equipment for use when other purification systems are not available.

Straws using a micro purification technology, with no iodine involved, are better suited to long–term use. The problem with all water purification straws is the real risk of local contamination of the mouthpiece. It is recommended that all the water in the straw is sucked up, rather than blown clear and you obviously have to keep the drinking end free of contamination from the end placed in contaminated water.

All manufacturers claim that 99.99 per cent of all water–borne bacteria, including Giardia and Cryptosporidium are removed.

Surviva–Pure Survival Straw by Web–tex
The highest current specification purifying straw is the Web–tex Surviva Pure Survival Straw (see above sidebar photos) which is NATO approved and is proven to:

Instantly removes chemicals, herbicides, pesticides, purification chemicals and sediments and trace metals.

Proven to remove water–borne disease, causatives, Cryptosporidium, Giardia, e–coli, viral disease–causing contaminants and Anthrax.

Capacity/Lifespan — filters up to 200 litres (53 US gallons).

BCB Aquastraw

BCB Aquastraw

BCB Aquastraw in use
The BCB Aquastraw purifier is NATO approved and produces microbiologically safe water from contaminated fresh water. It will purify approximately 50 litres (13 US gallons) of water. When water is sucked through the straw, it passes over iodine, charcoal and resin elements that act as a defence against bacterial and water–borne diseases. The straw is constructed as a series of filters, each building up resistance/cleansing/extraction properties against whatever may be present in the water source.

Because it uses iodine to purify the water it should not be used by pregnant women and people with thyroid conditions except in an emergency; it does not work in saltwater, brackish water or chemically contaminated water.

End of useful life is indicated by the straw becoming blocked. It has to be stored in dry conditions (below 30°C (86°F).

Weight 17 g (0.6 ounces) (22 g (0.78 ounces) in carrying tube); 18 cm (7.1 inches) long x 1 cm (0.4 inches); No waiting, just suck and drink; instructions are printed on the label.

There are several brands of purifying straw on the market designed for civilian use (business travellers, backpackers, etc.). These purifying straws are not designed to deal with highly contaminated water and you must read the specification claimed by a manufacturer very carefully. Make sure the straw bears a military approval rating, such as "NATO approved". It is not good practice to share drinking straws for obvious reasons.