Took this from CDC (
https://www.cdc.gov/healthywater/drinking/travel/backcountry_water_treatment.html):
Bacteria - (for example, Campylobacter, Salmonella, Shigella,
E. coli)
Methods that may remove some or all of bacteria from drinking water are:
1. Boiling (Rolling boil for 1 minute) has a very high effectiveness in killing bacteria; At altitudes greater than 6,562 feet, you should boil water for 3 minutes.
2. Filtration has a moderate effectiveness in removing bacteria when using an absolute less than or equal to 0.3 micron filter;
3. Disinfection with iodine or chlorine has a high effectiveness in killing bacteria;
4. Disinfection with chlorine dioxide has a high effectiveness in killing bacteria;
5. Combination filtration and disinfection has a very high effectiveness in removing and killing bacteria when used with iodine, chlorine, or chlorine dioxide and an absolute less than or equal to 0.3 micron filter (NSF Standard 53 or 58 rated "cyst reduction / removal" filter).
