Is It Time For Thru-Hikers To Ditch Their Smartwater Bottles?

Researchers from Columbia University and Rutgers University have found alarming numbers of plastic particles in bottled drinking water: more than 240,000 particles per liter on average, a concentration 10 to 100 times larger than previous estimates.

Although the health implications of consuming micro- and nanoscale plastics are still not fully understood, the findings cast doubt on the safety of drinking from plastic bottles, especially for thru-hikers who tend to store their water in old, beat up Smartwater bottles.

A Matter of Scale

This isn’t the first study to investigate the concentration of microplastics in bottled water. However, these new findings indicate that the total concentration of plastic particles is much higher than previously thought.

Why? Because this time, researchers also accounted for nanoplastics, particles that are even smaller than microplastics. Nanoplastics are so tiny that until recently, scientists have struggled to measure them accurately.

For reference, microplastics are particles between 1 and 5 microns in diameter. In contrast, anything smaller than 1 micron is considered a nanoplastic.

In the new study, which was published in the Proceedings of the National Academy of Sciences (PNAS) last Monday, the researchers developed a technique for measuring both micro- and nanoplastics in three common bottled water brands, identified only as Brand A, Brand B, and Brand C.

Shockingly, they found that microplastic accounted for only 10 percent of the plastic particles in the bottled water they tested. The remaining 90 percent was nanoplastic.

Do Water Filters Remove Plastic Particles?

This last point may be particularly concerning for thru-hikers. Nanoplastics can be so small that standard backpacking water filters won’t filter them out.

Filters like the Sawyer Squeeze can remove particles as small as 0.1 microns in diameter, including 100 percent of microplastics. But nanoplastics can be even smaller than 0.1 microns. So even after filtering, hikers are probably still consuming large numbers of plastic particles with their water.

Interestingly, the researchers also hypothesized that plastic components of water filters themselves could be contributing to plastic contamination in the water they tested. Granted, the reverse osmosis filtration systems used by bottled water companies are different from the hollow-fiber filters most hikers carry, but still. Interesting.

Implications for Thru-Hikers

What does this research really mean for hikers? It’s hard to say; there’s still a lot we don’t know.

We don’t know, for instance, how long it takes for plastic particles to shed into drinking water. How much time elapsed from when the water was first bottled to when the researchers in the PNAS study tested it? If a hiker fills a bottle at 9 a.m. and drinks it by 11 a.m., are they really getting the same dose of microplastic as they would from water that’s been marinating in plastic for weeks or months?

On the other hand, do plastic particles shed more rapidly from aged bottles that are getting reused again and again, scratched, dented, exposed to the sun, etc.? This seems likely, but again, we don’t know.

We also don’t know whether and to what extent other types of plastic, such as the textured polyurethane used in other popular ultralight containers (Cnoc Vecto, Katadyn BeFree), release micro- and nanoplastic into water. Are these types of containers a safer bet?  Who knows? Not us.

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Implications for Humans

Despite all these unknowns, it’s increasingly clear that plastics aren’t inert substances. Micro- and nanoscale particles from plastic containers can and do leach into food and water.

Plastic particles are all over. In the environment, they’ve been found everywhere from the clouds to the deepest depths of the ocean (and yes, they’re also in ground, surface, and tap water). Most of us have microplastics in our bodies too. Studies have detected them in blood, breast milk, stool, lung tissue, and more.

These particles come from many sources besides water bottles, but food and water containers are of special concern for those worried about the potential health impact of ingesting micro- and nanoplastics. The health effects of ingesting these particles aren’t well understood, but many experts believe there’s cause for concern.

Plastic Water Bottle Alternatives for Hikers

Unfortunately, there’s a reason backpackers love Smartwaters: they’re lightweight, inexpensive, and widely available. Every popular Smartwater alternative for hiking, from the classic Nalgene to collapsible options like the Cnoc Vecto or Evernew bag, is still plastic-based. Common sense suggests that these containers must also shed some amount of micro- and nanoplastic, but we don’t know how much.

Stainless steel and titanium water bottles are safer alternatives, but the former is heavy and the latter is expensive (and still heavier than a Smartwater). For instance, a 27-ounce Klean Kanteen stainless steel bottle weighs 7.5 ounces and costs $20. Meanwhile, a 1L titanium Vargo Bot — a clever piece of gear that doubles as a water bottle and a cook pot — weighs 5.2 ounces and costs $100.

While some hikers are probably willing to eat the price and weight penalty of one of these bottles, going all-metal is impractical for hikers who want a larger water carrying capacity. Consider that even in the water-rich eastern US, AT thru-hikers typically have at least two liters of water carrying capacity. In the arid west, PCT and CDT hikers may need to schlep four-plus liters at a time.

A single Vargo Bot is an excellent solution for replacing one Smartwater bottle. But if you need to replace four Smartwaters with Bots? That would set you back $400 and 21 ounces, a bitter pill for hikers accustomed to a water carry solution that weighs and costs next to nothing. (Not to beat a dead horse, but Bots also don’t mate with your water filter.)

Aluminum bottles exist and are lightweight, making them look like a tempting alternative to plastic. But aluminum bottles virtually always have a plastic liner to prevent the bottle from imparting an unpleasant metallic taste.

Where does this leave us?

Avoiding plastic altogether is a tall order for hikers trying to keep their base weights and budgets under control. Beyond drinking water, many hikers also store —and even cook — food in ziplocks, freezer bags, and Talenti jars.

It seems likely that plastic bottles will remain a thru-hiking staple for the foreseeable future. Just as some vegans and vegetarians reintroduce animal products into their on-trail diets for simplicity’s sake, hikers may reason that it’s impractical to eliminate plastic during a thru-hike and instead concentrate their efforts on reducing plastic in their civilized lives instead.

As ongoing research sheds light on the prevalence and health effects of microplastic, perhaps the UL industry will respond with a realistic solution for hikers keen to ditch their Smartwaters.

In the meantime, hikers can try to minimize the amount of plastic they consume by replacing disposable bottles more frequently, switching to more durable plastic containers such as Cnocs or Nalgenes, or investing in at least one metal bottle/Bot for use as a primary water container.

Featured image via Karl Halvorson.