Boiling

Boiling water kills all organisms that will make you sick.  The key is getting water to a rolling boil.  Allow it to cool and it should be safe to drink from a protozoal, bacteria and virus standpoint. 

Boiling requires a pot (or other container to heat up) and enough fuel to boil your water. 

Filtration 

Most quality filters are effective at filtering out Bacteria and Protozoa such as Giardia and Cryptosporidium.  

A few filters claim to filter out viruses, but filter times are often slow.

In the Pacific Northwest, the biggest concern is Giardia with Cryptosporidium being a close second.  Quality filters are generally adequate for our part of the world. 

Note that newer microfilament filters are damaged if they freeze. 

Be wary of filters not made by reputable manufactures. 

Chemical Treatment

Chemical treatment have long been a popular method of treating water.  It is light weight and simple to use. 

Chlorine (bleach) and iodine are great at treating water for Bacteria and Viruses.  These are NOT effective against Giardia or Cryptosporidium and are not recommended for treating water in our part of the world. 

Chlorine Dioxide is effective against Bacteria, Viruses and Giardia.  It requires a 4-hour contact time to treat Cryptosporidium and is therefore less than ideal and generally ineffective at treating Cryptosporidium.