How to Purify Water with Chlorine Dioxide Tablets

Chlorine dioxide is used by many city water treatment plants, but easy-to-use versions of chlorine dioxide are available for backpackers and travelers to purify any water from bacteria, viruses, giardia and crypto.

Despite the name, chlorine dioxide uses oxygen, not chlorine, to purify water. There are several brands of chlorine dioxide tablets available, including Katadyn Micropur MP1, Aquamira and Potable Aqua, but all the tablets are similar.

If you're backpacking or traveling in an area where you suspect the water needs purified from bacteria, viruses, giardia or crypto, here's how to use chlorine dioxide tablets.

Difficulty: Easy

Instructions

Things You'll Need:

• one-liter water container
• chlorine dioxide tablets

1. Fill a one-liter or one-quart container with water that needs treated.
   
   The tablets come individually wrapped in pouches made of sturdy foil. Don't remove a tablet until you're ready to use it. Slit open the foil with a knife or scissors, drop one tablet into the water and seal the water container. The tablet will begin to fizz and release chlorine dioxide gas.

2. After a few minutes, turn the container upside down and unscrew the top slightly to let treated water dribble over the threads and rim of the container, to purify them as well.

3. How long you need to wait before drinking the purified water depends on how cold or dirty (muddy) the water is. Clear water at summer temperatures (68 degrees F) will be purified in 30 minutes.
   
   Water that's very cold (under 40 degrees F) and dirty or muddy requires a wait of four hours, which is what you'll probably see listed on the package, since the label requires the longest time to be listed. Chlorine dioxide will purify all water of bacteria and viruses in less than 30 minutes, but the longer time for cold dirty water is required to purify it of crypto as well.

4. After the wait time is up, the water is ready to drink.

Tips & Warnings

• Most people report the taste of water treated with chlorine dioxide to be good. If the water has a slight "swimming pool" taste soon after being treated, leaving the container uncapped for a short while, waiting a little longer, or pouring the water from one container to another may help.
• Chlorine dioxide won't purify water from heavy metals or agricultural chemicals, so if you suspect those, you'll need to use a filter as well.

Resources

• Chlorine dioxide and other ways to purify water