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Water Filters & Purifiers

Bottled Water
Filters vs. Purifiers
Miox Water Purifiers
SteriPEN Water Purifiers
Water Purification Tablets
What is Cryptosporidium? CDC link
What is Giardia?  CDC link

Bottled Water
 Cryptosporidium is highly resistant to chlorination and one of the most common organisms transmitted by water.  A very sophisticated purifier is required to remove it.

Reliable bottled water:  One of the following treatments or certifications will be indicated on bottled water free of Cryptosporidium.

  • Reverse osmosis

  • Distillation

  • Absolute 1 micron or smaller filtration

  • “One micron absolute” filtration

  • Tested and certified by NSF Standard 53 or NSF Standard 58 for cyst removal (or reduction)

Unreliable bottled water:  The following water bottle labels or indicated treatments are not a guarantee of Cryptosporidium free water.

  • Filtered

  • Micro-filtered

  • Carbon-filtered

  • Particle-filtered

  • Multimedia-filtered

  • Ozonated

  • Ozone-treated

  • Ultraviolet light-treated

  • Activated carbon-treated

  • Carbon dioxide-treated

  • Ion exchange-treated

  • Deionized

  • Purified

  • Chlorinated

Bottled water from the following sources may be reliable if the source has been protected from surface contamination:

  • “Well water"

  • "Artesian well water"

  • "Spring water" 

  • "Mineral water"

Filters vs. Purifiers
Not all water filters are water purifiers. Some filters are not capable of removing viruses and bacteria which are much smaller than parasites.  A desirable purifier removes or destroys bacteria, viruses and protozoa including Giardia and Cryptosporidium. 

"Reverse-osmosis filters provide protection against viruses, bacteria, and protozoa, but they are expensive and larger than most filters used by backpackers, and the small pores on this type of filter are rapidly plugged by muddy or cloudy water. In addition, the membranes in some filters can be damaged by chlorine in water."

"Microstrainer filters with pore sizes in the 0.1- to 0.3-μm range can remove bacteria and protozoa from drinking water, but they do not remove viruses. To kill viruses, travelers using microstrainer filters should be advised to disinfect the water with iodine or chlorine after filtration, as described previously."

Some microstrainer filters come with an additional installed component, such as an iodine-impregnated resin.  Iodine-impregnated resins are effective against bacteria and viruses. 

In summary, effective filters or purifiers are:

  1. Reverse osmosis purifiers.

  2. Or microstrainer filters with iodine impregnated resins.

Travelers' Health: Yellow Book Health Information for International Travel, 2005-2006, Chapter 2 (CDC)

For a review of water filters and bottled water see the CDC Fact Sheet on "Preventing Cryptosporidiosis: A Guide To Water Filters & Bottled Water."

Reverse osmosis and microstrainer purifiers can be found at many sporting goods stores and many online stores.  Examples of these purifiers can be seen at www.Katadyn.com.

Miox Water Purifiers
Miox stands for "mixed-oxidants" and can be used in large water purification needs or as a shirt pocket pen that can purify up to four liters of water at a time.  It reportedly kills Giardia and Cryptosporidium, as well as bacteria and viruses.  This device has batteries that operate when a small amount of rock salt and water are placed in their chambers.  The resultant oxidant brine solution is then poured into one to four liters of water.  The solution must stand for one to four hours depending on the volume.  Cloudy water will remain cloudy, but will be purified.  Cost is moderate at about $120  in sporting goods and online stores.

SteriPEN Water Purifiers
This is a unique 8 ounce pen with 4 AA batteries that emits ultraviolet light reportedly killing bacteria, viruses, and protozoa including Giardia and Cryptosporidium.  The light emitting stem is dripped into clear water and held there for about one minute to treat 16 ounces of water at a time. The water cannot be cloudy or discolored, however.  It could be helpful in hotel rooms with a questionable water source and other clear water applications.  The cost is moderate at about $149 in sporting goods and online stores.

Water Purification Tablets
There are many brands of water purification tablets available at pharmacies and sporting goods stores.  Their effectiveness often can not be fully determined by reading the container label.  Chlorination and iodination tablets can not be relied upon to remove Cryptosporidium or even Giardia in cold water.

Micropur MP1 is a chlorine dioxide tablet that reportedly meets EPA Water Purifier Test Standards to control viruses, bacteria and cysts, including Giardia and Cryptosporidium.  Each tablet treats 1 liter of water.  For full protection of clear water it should stand for 30 minutes.  For dirty water it should stand 4 hours before use.  Made by Katadyn.

 

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