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Curiosity 8 – Water filters/treatments?

At the Philmont Scout Ranch they have crews treat the water.  They give you Katadyn Micropur tablets for water treatment.  I also thought it was interesting that Outdoor Gear Lab did not have the Katadyn Micropur tablets in its review (titled/dated, best of 2021).

I have seen a number of VLOGs using a Sawyer mini or Squeeze.  Usually, it seems folks choose the Squeeze Mini.  I have a Sawyer Squeeze (not the Mini) as the flow rate is better than the Mini.

And some chemical treatment options don’t handle Giardia or Crypto (or take a while to handle those protozoa; I think that is correct for these).  Also, a lot of filter/treatment options do not handle chemicals.

Of course, there is always boiling.  The number I have seen is at least 3 minutes (after bringing the water to a rolling boil; continue to boil for those number of minutes).  I usually look at 5 minutes as five is an easy number to remember.

There are so many options out there.  Of course, there is always boiling.

So, curious what folks know/think about water filters/treatments.

  • Do you understand the items that different filter/treatment systems filter or treat (i.e., protozoa, bacteria, viruses, chemicals)?
  • Do you filter or treat the water?
  • Do you use a treatment (i.e., chemicals or tablets)?
    • Which do you use?
    • And which type (I.e., Chlorine Dioxide)?
  • Do you use a filter?
    • What type (i.e., gravity, squeeze or pump)?
    • What do you think about Sawyer Squeeze or Mini?
    • What do you think about the MSR Guardian (pump)?
      • Noted this one specifically as it handles more items than most pump filters.
    • What about gravity systems (i.e., Platypus GravityWorks)?
  • What about other filtration/treatment (i.e., LifeStraw or Ultraviolet).
  • Do you use something different if in a group?


19 Replies

boil, baby, boil!  Just bring it to boil and then consume (or cool off).  I have seen recommended boiling times of as long as 15 minutes, but I will take the advice of Dr. James Wilkerson, author of Medicine for Mountaineering, who point out that pasteurized milk is heated to 160F.  He is comfortable with simply bringing water to a boil.  I have a filter, rarely used, and some tablets, just in case. 

Toxic algae present a real problem.  What should one do if the choice is toxic critters or no in water at all, with  possible fatality due to dehydration.?  Desert rat that I am, I have faced this choice occasionally and I have always drunk the water.  I have never suffered any noticeable consequences.

Some years ago, I was a member of an expedition exploring and mapping caves in southern  China.  All twelve members of our group ate locally prepared and drank the local water, which was routinely boiled, for a solid month.  No illnesses occurred.  I would have known, because I was the group's EMT....

Besides, how else are you going to make tea or coffee??? 

Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.

Depending on the trip, day hikes I always have a Sawyer Mini in my pack, but over-nights I'll carry the Sawyer Squeeze. I always have Aquatabs in my emergency pouch. Even on day hikes, I'm always carrying my Jetboil MicroMo stove. My hiking is currently limited to the Northeast US, so I'm not concerned about carrying a water purifier.


"My hiking is currently limited to the Northeast US, so I'm not concerned about carrying a water purifier."

Could you please expand a bit on those remarks?  I ask because as  a western desert rat, hiking in the industrialized, heavily populated NE, I would be very concerned about pollution.  I have done maybe two miles of hiking in the NE - Acadia NP

Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.

I was working on a reply that had a write-up that I did in 2017 and early 2018 for the Scout troop.  But, there were issues.  i am assuming it was too long (too many bytes).  So, I will divide it into three parts.



It should be noted that most information out there indicates that viruses are not likely or not to be too concerned about in North America (some sources note this as United States and Canada).  Viruses tend to occur where water is contaminated by untreated or poorly treated waste water or exposure to contact with infected folks.  So, do your research on the area where you plan to be.

"Viruses are very species-specific. In other words, they don’t infect just any host they come in contact with. If you catch a virus, its source was most likely another human being. Therefore, human-specific viruses tend to be less present in settings where there’s little human traffic. In addition, in developed regions—like much of North America and Europe—advanced sewage systems and generally good hygiene practices have greatly reduced the risk of viral outbreaks.

But in much of the developing world, viruses still pose a significant risk. Where sanitation is poorly maintained, uncontrolled sewage can contaminate drinking water. For international travelers, this risk is compounded by the fact that good medical services can be hard to come by should you get sick. Most viral infections aren’t life threatening in healthy adults, but the ability to rehydrate your body with safe drinking water is critical.

Even as a traveler in the backcountry, however, you must be observant of your surroundings, and recognize where others may not have practiced clean tactics. Popular camp spots tend to be higher-risk zones. When people neglect to dispose of their waste properly, viruses can be present in the natural water sources "  This is from MSR's website (Summit Register).

Below we will go into a bit of the details for some options and products.  This is in no way an exhaustive list.

Again, it is always best to read the instructions on the product.  Because if not used correctly, you risk exposure to the very pests that you are trying to avoid.

First off, we want to start with the rule that you should be drinking about 5 liters of water a day.

So, you want to know how to treat your water.  If you think it might be potable (safe drinking) water, you should confirm that first.  If you cannot confirm it, treat it.


Chemical treatments

We want to discuss more about the chemical options (some of the products and some of their details).  Starting with some of the chemical treatments which are Chlorine (aka, bleach), iodine and Chlorine Dioxide.  Chlorine Dioxide and some other forms of chlorine (i.e., NaDCC) are safer than bleach and iodine.

Chlorine Dioxide

Chlorine dioxide is one of several oxides of chlorine.  Don't you just love some folk's definitions.  This is really an oxidizer or oxidizing agent.  "Chlorine dioxide is a neutral chlorine compound. It is very different from elementary chlorine, both in its chemical structure and in its behavior. One of the most important qualities of chlorine dioxide is its high water solubility, especially in cold water. Chlorine dioxide does not hydrolyze when it enters water; it remains a dissolved gas in solution. Chlorine dioxide is approximately 10 times more soluble in water than chlorine."  Pulled from Wikipedia.


"Sodium dichloroisocyanurate (INN: sodium troclosene, troclosenum natricum or NaDCC or SDIC) is a chemical compound widely used cleansing agent and disinfectant. It is a colorless, water-soluble solid. The dihydrate is also known (51580-86-0) as is the potassium salt (2244-21-5)."  Pulled from Wikipedia

"NaDCC, also known as Sodium Dichloroisocyanurate or Troclosene Sodium, is one form of chlorine used for disinfection. It is often used to treat water in emergencies and is now widely available for household water treatment."  Pulled from akvopedia.

Aquatabs (tablets)

This treats bacteria, viruses and cyst (i.e., Giardia).  It reduces bacteria by 99.9999%, viruses by 99.99% and cyst (Giardia) by 99.9% in 30 minutes.  The tablets work in clear water.  If the water is murky it needs to be filtered first.  It does not treat Crypto.  After you put in the tablet you need to give it a few shakes first.  The active ingredient is NaDCC.

Potable Aqua Chlorine Dioxide (tablets)

The active ingredient is Chlorine Dioxide.  This treats bacteria, viruses, cysts (Giardia) and Crypto.  Requires 4 hour treatment.

Katadyn Micropur (MP1) (tablets)

The active ingredient is Chlorine Dioxide.  This treats bacteria, viruses, cysts (Giardia) and Crypto.  15 minutes kills viruses and bacteria, 30 minutes kills Giardia, and 4 hours kills Crypto.  Note:  This is what Philmont uses.

Potable Aqua Iodine (tablets)

The active ingredient is Iodine.  This treats bacteria, viruses, cysts (Giardia).  Iodine is not effective on Crypto.  Requires 30 minutes for treatment.

Iodine disperses slower in colder water.  So, it may take longer to treat or is less effective.  Important:  Water that has been disinfected with iodine is NOT recommended for pregnant women, people with thyroid problems, those with known hypersensitivity (allergic) to iodine.  Not recommended for continuous use for more than a few weeks at a time.

Aquamira Water Treatment Drops

The active ingredient is Chlorine Dioxide.  This treatment is in liquid form and comes in two parts (Part A and Part B).  This treats bacteria, viruses, cysts (Giardia) and Crypto.  Part A and Part B must be mixed together first before adding it to the water.  Read the instructions.  Requires 5 minutes before adding the mixture (Part A and Part B) to the water.  Requires another 30 minutes for treatment.


Filters are one alternative to chemicals.  Most filters do not handle viruses.  The reason is viruses are 0.004 to 0.1 microns in size.  And, most filters handle sizes down to 0.1 microns.  Generally, filters handle bacteria and cysts (Giardia and Crypto).

Sawyer Squeeze

Not the "mini".  The mini does not provide a good flow rate.  It is more of a drip rate.  The Sawyer Squeeze (Sawyer PointONE filter) handles anything down to 0.1 microns.  The flow rate (once the filter is wet) is 1.7 liters per minute.  Sawyer's website also mentions another filter the Sawyer PointTWO which handles viruses down to 0.02 microns.  Look at either the Sawyer Squeeze Water Filter system (2-32 fl. oz. bags) or the Sawyer Squeeze Water Filter Plus (2-64 fl. oz. bags).  Note these are the same filter just different bags.  Both of these also come with items that can turn it into a gravity feed system and a syringe for back-flushing the filter.

Special note:  Sawyer also sells the Sawyer S3 Purifier which handles heavy metals, viruses, bacteria, protozoa, chemicals and pesticides.  Squeezable bottle with screw on filter.

Platypus GravityWorks

Platypus sells this filter system in a 2 liter and 4 liter size.  It is the bags that are in the 2L or 4L sizes.  The filter is the same.  It filters down to a 0.2 microns size.  It removes particles, protozoa and bacteria down to 0.2 microns in size, including giardia, salmonella, crypto and more.  There is a dirty (water) bag and a clean (water) bag.  It has a flow rate of 1.75 liters per minute.

MSR Guardian Purifier

This is a pump filter.  You have to pump.  So, some work required for filtering water.  This is one of the higher rated pump filters.  The flow rate is 2.5 liters per minutes.  It removes viruses, bacteria, protozoa and particulate.  It filters down to 0.02 microns.  Yes, it removes viruses.

LifeStraw Water Filter

This is a straw.  You can drink straight from the water source.  It filters down to 0.2 microns.  It removes bacteria, protozoa (including Giardia and Crypto).


Sorry make that four parts.  And the issue mauy have been broken links (RULs).

Other purifying technologies

One of the other mechanisms is Ultraviolet (UV/UV-C) light.  UV-C safely sterilizes clear water by destroying protozoa (including Giardia and Crypto), bacteria and even viruses.

SteriPEN ultra Water Purifier

Uses UV-C light to take care of pests.  Works on clear water.  Sterilizes 32 fl. oz. (1 liter) in 90 seconds (1 1/2 minutes).


I was running the Sawyer Micro for a couple of years without issue.  This past November on a trip, it started to freeze and then I had one more day with it on trail.  But that trip I noticed a decent drop in flow rate.  So now I'm running a Sawyer Squeeze.  I also bring Aqua Mira drops, which I use as an additional level of purification (from sketchy water sources), and as a backup (in conjuction with a bandanna) if the filter fails.


I have never worried about protozoa/bacteria/virus factors you mentioned. I use a sawyer squeeze for solo trips. I prefer it over the mini for flow rate, as you mentioned, and it is still incredibly light. I use a  katadyn pro hiker when with my family, because I find it faster for filtering volume. I've never once gotten sick or had any issue with either of them. I also carry iodine tablets as an emergency back up in case my filter breaks. I think it is good to at least know how long you should boil water to make it safe in case of an emergency.