How To Purify Water on a Long Trek?

Q: What should I use to purify water on a long trek?
— Olivia, Denver, Colorado

A: On a long trek, you can’t carry gallons of drinking water from home. You must figure out a way to rid bacteria and protozoa from water in your environment to make it safe to drink. Here are a few options.

Heat water to a rolling boil for a full minute or drop in some type of chemical treatment tablets, which often take at least a half hour to work. You can also try ultraviolet light wands, which destroy the DNA of bacteria and viruses so they can’t reproduce when you ingest them.

Another quick method involves filters. Water filtration systems force untreated water through a screen with holes so small bacteria cannot pass.

The MSR TrailShot Pocket-Sized Water Filter ($63, msrgear.com) can force up to 1 liter of water through its handheld filter every minute. It has a spout you can drink from, or you can use it to refill your water bottle. The LifeStraw Peak Series Straw ($25, lifestraw.com) also fits easily in your pack, and its filter lasts up to 5 years. It removes tiny organisms that can make you sick and filters out sand and microplastics.