When you just don’t want to carry anything else in your day pack or your thru hike gear, then you can opt to rely solely on chlorine dioxide tablets to treat your drinking water. Not everyone can or wants to shell out money for a fancy gravity purifier or drinking straw filter and ClO2 tablets can come in handy in a pinch.

I’ve used ClO2 tablets for years.  We’re issued them in the Army for cantine water.  They’ve also come in handy being in countries who serve water that can’t totally be trusted.  Taste doesn’t matter that much to me as long as the water doesn’t make me sick and keeps me hydrated.

No Guarantees in Water Treatment

There’s no guarantee that you’re going to kill everything harmful for you in the water you’re drinking with any treatment type.  Just like pump based filters are heavy and can build mold in them if not washed and maintained, life straw type filters are less effective against water with lots of suspended stuff floating in it, ClO2 has it’s pros and cons as well. For instance, did you know that ClO2 tablets can take up to 4 hours to kill protozoa like cryptosporidium?

Activated carbon doesn’t kill viruses, etc, etc.

ClO2 and Other Chemical Water Purification Processes


In most cases, you’ll buy you ClO2 tablets that come individually wrapped in an aluminum or tin foil type of structure.  (Yes, the same frustrating packaging for over the counter meds).

Take care not to let your tablets get pushed around and smashed because they’ll crumble.  I don’t have to you how difficult it is to get powder into a water opening rather than a tablet.

Sometimes it helps to have a utility tool available to open the packaging and get the tablet out.  (Yeah, it’s frustrating sometimes).

Time and Effectiveness

ClO2 tablets will take about 30 minutes to kill protozoa and bacteria but (like mentioned above) can take up to 4 hours (and longer) if the water is turbid or has lots of suspended particles and also cryptosporidium.

If you wanted to shorten the process, there are filters that screw on top plastic bottles that will kill the cryptosporidium prior to ClO2 treatment.

Try to drink 16 to 24 ounces of water per hour in very warm weather depending on your exertion level. That works out to about 1 quart (liter) every 2 hours.


The taste is a little off and some people even say it tastes “bad”.  It’s not too far away, though, and staying safe, healthy, and hydrated is the name of the mission here.