What are some of the limitations of activated carbon in water treatment devices? – Cascade Designs

Activated carbon has long been used in treatment devices because of its adsorptive properties—it attracts many types of molecules to its surface and traps them. Carbon is also highly porous, so a small piece provides lots of surface area.

For these reasons, activated carbon is great for catching many contaminants that are so small—tiny molecules—that they pass through a microfilter. These include tastes, odors, pesticides, herbicides and pharmaceutical byproducts. Carbon can also pull out some heavy metals.

However, it’s important to know that activated carbon has its vulnerabilities. At MSR, we believe carbon is best used as a secondary removal media—another level of protection after you’ve filtered out (or purified water of) microbes. This is because:

1.) When the water’s contamination level is high, the surface area fills up quickly;
2.) If the water’s flow rate is too fast, carbon is less likely to catch all the contaminants;
3.) Adsorptive filters, like carbon, don’t indicate when their surface is full—you have no way of knowing when it’s no longer doing its job.

Therefore, treatment devices that rely solely on adsorption to remove the microbes run the risk of letting some of those immediate threats through to you.

For these reasons, MSR products don’t rely on adsorption/carbon to remove the microbes. The MSR MiniWorks, for example, uses a ceramic element to filter out the bacteria, protozoa and sediment, and then activated carbon to reduce tastes, odors and chemicals.

Activated carbon can make water more enjoyable to drink and adds an extra level of safety, but it’s still important to research where you’re going, and the types of filters and purifiers ideal for those environments. A quick call to the ranger station can inform you of any particular local risks. Unfortunately, not even activated carbon will remove everything. But in most wilderness regions, a high-quality filter or purifier can get you out and back—with nothing more than stories of great adventure to share.

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