Boil wilderness drinking water; the cited travel guidance recommends a full minute even at usual travel elevations
The cited CDC travel guidance says waterborne disease organisms are inactivated within seconds at boiling temperature; a full minute adds a margin for recognizing boiling. At usual travel elevations it does not require extra time solely for altitude. Filters or disinfectant tablets are alternatives when boiling is impossible, but each has gaps. Clear streams and snowmelt can still contain parasites.
What it takes
Carrying a stove and fuel adds weight.
What you may gain
Organisms causing illness through drinking water are inactivated within seconds at boiling temperature. The cited source disputes the assumption that boiling is too cool at ordinary travel altitudes.
Context & considerations
The same page states that holding water at 60°C for 30 minutes is effective; boiling is a visible endpoint requiring no thermometer. If boiling is unavailable, use a filter or chemical disinfectant, recognizing that each misses some pathogens. Appearance does not establish safety: clear stream water or snowmelt may contain parasites.
Research & references
US CDC. Yellow Book: Water Disinfection for Travelers. It recommends a full minute to allow for user variation and a safety margin, and states that although boiling temperature falls with elevation, at common travel elevations it remains well above temperatures required to inactivate enteric pathogens. https://www.cdc.gov/yellow-book/hcp/preparing-international-travelers/water-disinfection-for-travelers.html