Best Chemical Water Treatments for Backpacking
All you need to know about this OG water purification solution.
We’re usually focused on reviewing the latest and greatest gear here at Better Trail, but sometimes it’s worth taking a look at the outdoor essentials of yesteryear—especially if they still deserve consideration for your kit. A perfect example of this is chemical water treatments. Once standard issue in just about every backpacker’s inventory, they’ve largely been relegated to emergency bugout bags and stories from your aunt who did a four-day trip in Yosemite in the 70s. Chemical water treatments are still widely available today, though, and they occupy a unique niche in the gear world. Here’s why you should still give them some consideration.
What are Chemical Water Treatments?
Unlike modern backpacking water filters, which remove bacteria and protozoa by forcing water through microscopic pores, chemical treatments work by killing harmful organisms outright. In addition to targeting bacteria and protozoa, they also neutralize viruses—technically earning chemical treatments the designation of “purifiers.”
Iodine and chlorine dioxide are the chemicals commonly used to get the job done, which they do reliably and safely. However, there are some notable drawbacks to using a chemical treatment rather than a filter, mostly related to speed and taste—we’ll get more into that below.
Chemical Water Treatment Benefits
The biggest reason to consider using a chemical treatment for making potable water is how light and packable they are. They generally weigh 3 ounces or less and come in droppers or jars that are smaller than the palm of your hand. (The Katadyn Micropur MP1 tablets even come in flat packaging that weighs 0.9 oz. altogether.) This makes them extremely portable, which works well for use as an emergency backup water plan; if your filter goes on the fritz, having a chemical treatment in your pack will cost almost nothing from a weight and bulk perspective.
Having a purifier at your disposal can also come in handy if there’s a chance viruses are in your water source, as filters don't have microns small enough to eradicate those pesky buggers. Carrying a chemical treatment on your travels abroad or even as an additional layer of protection in suspect backcountry areas can provide an extra dose of safety. If you’re at all concerned that water will be affected by human runoff, a light, packable chemical treatment is an easy solution.
Chemical treatments are also cheaper than water filters—but only up to a point. A jar of Potable Aqua iodine tablets will only run you $10, which is extremely affordable as far as essential backpacking gear goes; the Aquamira Water Treatment, which uses chlorine dioxide, isn’t much more expensive at $15. However, the former can only treat up to 24 liters of water, while the latter can purify 114 liters. When you consider that filters such as the (still fairly inexpensive) Platypus QuickDraw cost $40 but can treat up to 1,000 liters of water, or that the LifeStraw Peak Squeeze ($44) has a filter lifespan of 2,000 liters, chemical treatments turn out to be the far less cost-effective solution in the long run, especially if you backpack a lot.
Chemical Water Treatment Shortcomings
However, opting for a chemical treatment over a filter has major downsides. The one that gets the most press is how slow they are compared to mechanical filters. Whereas light, simple squeeze filters like the QuickDraw and the Peak Squeeze can produce up to 3 liters of clean water per minute, you’ll have to wait 20 to 30 minutes for chemical treatment to kill harmful microorganisms. And that’s on the shorter end. Katadyn recommends waiting 4 hours for Micropur tablets to work if the parasite cryptosporidium is present.
If you’re parched and need hydration ASAP, waiting even a moment after you reach a water source can be a huge bummer. If you’re purifying on the go while hiking fast, you’ll have to carefully plan out which reservoirs or bottles you’re carrying will be used for water that’s drinkable now and water that’s drinkable in the future. Plus, while there used to be a valid argument that using drops or tablets prevented the agony of pumping a filter until your arms were sore, modern squeeze filters and gravity models make the process nearly effortless.
Another drawback is that chemical treatments do not include filters to remove tiny particulate matter from your drinking water. Unless you want a mouthful of grit, you’ll have to employ a pre-filter for drinking from anything dirtier than a clear, pristine wilderness water source. Common pre-filters include coffee filters or handkerchiefs, but that’s just another step on the road to potable water that you’ll have to work into your routine.
Finally, many chemical water treatments impart a taste to the purified water that some hikers won’t like. Some products do their best to counteract it—you can buy Potable Aqua Neutralizer Tablets to remove the taste of iodine, and flavored electrolyte tabs can cover up the musk—but this could partially defeat the purpose of sipping from a cold, remote mountain stream.
Chemical Water Treatment Comparisons
Now that you know the ins and outs of chemical purifiers, here are three that you’ll commonly see on the trail, along with how they stack up against each other.
Potable Aqua Iodine Tablets ($10)
Potable Aqua iodine tablets have the distinction of being the cheapest product of the bunch, as well as the easiest to use: You just pour out however many tablets you need into the palm of your hand (two tablets treat 1 quart of water), dump them in your dirty water vessel, and wait 30 minutes. Potable Aqua easily tasted the worst out of the chemical treatments we tested, though, and unlike the chlorine dioxide treatments, does not eradicate Cryptosporidium. The brand sells neutralizing taste tablets to help with the former, but you have to wait an additional 3 minutes for them to work after the initial 30 are up.
Aquamira Water Treatment ($15)
Aquamira's liquid form factor makes it a bit more involved than Potable Aqua or Katadyn Micropur, both of which come in tablet form. Instead, Aquamira is packaged in two small bottles: one (“Part A”) contains chlorine dioxide, and the other (“Part B”) contains a phosphoric acid activator. To purify water, mix equal amounts of Part A and Part B in the included mixing cup—7 drops each to treat 1 liter—wait for the solution to change color (about 5 minutes), and then add it to dirty water and wait 30 more minutes (or 4 hours for Cryptosporidium) before you drink.
Aquamira is better than tablets for treating large amounts of water for big hiking groups, as long as you make sure you count the chemical drops correctly both going into the reaction and coming out of it. It also avoids the yucky iodine aftertaste, though those with fine palates will still detect chlorine. But the downside to Aquamira is that you run the risk of leaking bottles (we have the bleach stains to prove it), and measuring out small drops of liquid may be the last thing you want to do on a hot, dry trail day when you’re thirsty.
Katadyn Micropur Purification Tablets ($18)
Like Aquamira, Micropur also uses chlorine dioxide, but it comes in tablet form. Somewhat annoyingly, these are individually packaged, which makes the product fussier to use than Potable Aqua. (Not to mention more wasteful.) One of our testers also noted that the one-tablet-to-1-liter-of-water ratio isn’t ideal if you want to filter a half-liter, since the tablets are so small they're almost impossible to break. (Comparatively, you can just use one Potable Aqua tablet for half a liter of water.) Micropur’s flat packaging is the least bulky option, and it doesn’t have that iodine taste, but it’s also the most expensive. As with any chemical water treatment, tradeoffs abound.
The Best Backpacking Water Filters
Chemical water treatments may no longer be the default choice for most backpackers, but they still earn their place as ultralight backups, international travel solutions, and virus-killing insurance policies. That said, for most backcountry trips—especially where speed, taste, and convenience matter—modern water filters offer a far better day-to-day experience. If you’re ready to explore today’s fastest, lightest, and most versatile filtration systems, head over to our guide to the Best Backpacking Water Filters, where we break down the top squeeze, gravity, and bottle-based filters to help you find the right solution for your adventures.
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