waterproof hiking boots–or not? How to choose

Waterproof hiking boots may—or may not—be the best choice for your hikes. However, it's getting harder for hikers to make sense of their options with all the myths and misunderstandings about waterproofing and breathability that litter the internet. This post covers the basics on waterproofing and breathability to help hikers understand when they might choose waterproof hiking boots or non-waterproof options, especially non-waterproof trail running shoes.  

waterproof hiking boots vs non-waterproof trail runners

Hikers have two reasonable options for keeping their hiking feet dry.

Waterproof hiking boots and (to a lesser extent waterproof hiking shoes) usually work pretty well for most hikers. The best waterproof hiking boots have membranes that will seal out rain and snow while releasing evaporated moisture vapor. The tradeoffs are that waterproof footwear runs slightly warmer, traps in liquids if it gets swamped, and doesn't dry as quickly. 

Those limitations have led some hikers—especially thru-hikers and ultralight backpackers—to pair non-waterproof trail running shoes with Merino blend socks that wick moisture and insulate while wet. Non-waterproof trail runners won't run as warm as waterproof hiking boots, so they'll potentially reduce sweat (depending on your metabolism, the temperature, and the humidity). Plus, they'll dry faster than waterproof hiking boots if they do get swamped. The trade off is that it only takes a couple steps in a puddle or wet grass to soak hikers' feet in non-waterproof footwear. 

One rule of thumb is to determine if your feet are more likely to get swamped with outside moisture or inside moisture.

If you're more likely to get wet from rain, mud, wet vegetation, or snow, waterproof hiking boots usually make the most sense. However, if you're more likely to get swamped with sweat—or know your feet will get soaked no matter what—non-waterproof trail running shoes may be the lesser of two evils, due to their faster drying times.

For example, waterproof hiking boots make the most sense for 90% of my day hikes. However, my feet may stay marginally drier in non-waterproof trail runners if I'm hiking in hot and humid environments, hiking or backpacking all day (which generates extra sweat), or tackling trails with deeper water or regular water crossings. 

Many experienced hikers choose both. That is, they'll own waterproof hiking boots for winter and wet shoulder season hikes and non-waterpoof trail running shoes for hot summer hikes. 

That's the short answer. The longer answer requires a sound understanding of waterproofing and breathability. 

 "waterproof" and "breathable" hiking footwear

As an outdoor industry professional, I know that many hikers are confused about waterproofing. And almost everyone mistakenly believes that “breathability" means the same thing as ventilation, air permeability, or moisture-wicking. 

I did, too, until I started working in a hiking and backpacking shop. Thanks to my outdoor industry training, I now have a better understanding of waterproofing and breathabliity to pass along to hikers.

What is a "waterproof" hiking boot?

Waterproof hiking boots and shoes have a waterproof membrane inside of them that prevents water from leaking through under normal pressure. That's what makes them "waterproof"—not some spray or surface coating. 

GORE-TEX remains the industry standard for durable and breathable waterproofing. GORE-TEX is a thin sheet of ePTFE (expanded polytetrafluoroethylene, aka Teflon)— and now ePE (expanded polyethylene)*—with 9 billion microscopic pores per square inch. Each pore is 20,000 times smaller than a single water droplet. That keeps liquid from seeping through the membrane (unless there's significant water pressure). At the same time, these microscopic pores are 700 times larger than chains of water vapor molecules in their gaseous state. This allows the membrane to "breathe"—to transmit evaporated water vapor to the atmosphere—when the heat and humidity are greater inside a boot/shoe than outside it. 

Are hiking boots really waterproof?

Yes, waterproof membranes should prevent moderate to heavy moisture from seaping through your hiking boots and shoes. Most brands meet external standards for waterproof gear while GORE-TEX waterproofing is guaranteed for life. 

European brands can't call hiking boots "waterproof" without hydrostatic head tests that meet EU standards. Hydrostatic head tests measure how much water volume (in mm) or water pressure (in PSI) a membrane/laminate can hold for 24 hours before it leaks. The EU defines a 1,500mm water column as "water resistant" (not waterproof), a 5,000mm water column as "very waterproof," and a 10,000mm as "highly waterproof." These measures are proxies for moderate (5000mm) to heavy (10,000mm) rainfall. 

US brands can set their own definitions of "water-resistant" vs. "waterproof." However, most good brands meet or exceed EU standards in order to export their products. For example, GORE-TEX has a hydrostatic head of at least 28,000mm—more than quintuple the EU's waterproof threshold—and conducts more active waterproofing tests that simulate hiking. 

It's possible that sustained hikes on splashy or slushy trails can overwhelm a waterproof-breathable membrane after several hours. Even then, there's a decent chance that water worked its way in through moisture-wicking pants or socks—and never penetrated our footwear's waterproof membrane. 

So, why do my feet get wet in waterproof hiking boots?

Hikers' feet usually get wet in waterproof hiking boots and shoes because

These are examples of hiker error more than waterproofing failure. I've personally tested more than 50 waterproof boots and shoes over 15,000+ miles of hiking and only suspect that the waterproofing failed in only three of them. In many cases, hikers can prevent (or significantly delay) wet feet by wearing waterproof pants or gaiters or restoring the DWR finish on their boots and shoes.

"There's no such thing as waterproof"

Many hikers and bloggers claim "there's no such thing as waterproof." However, most of their examples have nothing to do with water leaking through a waterproof membrane or laminate—which is what "waterproof" means. 

If your feet get wet because rain runs down your legs or your hiking pants wick in moisture from wet vegetation, rain, or snow, that does NOT mean "hiking boots aren't really waterproof." Did water leak through the waterproof membrane? Nope. The failure point isn't the waterproofing—it's shorts or moisture-wicking hiking pants.

It's also hiker error—not a waterproofing failure—to flood waterproof hiking boots in a deep puddle or stream crossing. Waterproof boots and shoes are not made to be submerged fully since the waterproofing doesn't extend to the top.  

Others believe their waterproofing "fails" or "wears off" when water no longer beads up and runs off the surface of their waterproof hiking boots. But that coating is not the waterproofing—it's the DWR (which is easy to restore—see above). 

Finally, many bloggers lead hikers to believe that their feet will get soaked with sweat because "waterproof hiking boots aren't breathable." With a smug tone, they'll predictably post something like this: "No matter what [marketers or GORE-TEX] claims, waterproof hiking boots aren't breathable because the waterproofing blocks airflow and prevents sweat and water from wicking out."

The problem is, breathability does NOT refer to air flowing through large pores or synthetic mesh to ventilate hikers' feet. Nor does breathability refer to wicking liquids to the outside air to evaporate. 

What does "breathable" really mean?

According to reps from The North Face, Arc'teryx, and other leading brands, 99% of people use the word "breathability" incorrectly—including most outdoor gear websites. Almost everybody confuses breathability with air permeability or ventilation or (sometimes) moisture-wicking—when it's none of the above.

In the outdoor industry, "breathability" is a technical term for "moisture vapor transmission" or "evaporative transfer." It refers to water that's already evaporated—not to airflow (ventilation, air permeability) or liquids (water, sweat). Contrary to popular belief, breathability also has little to do with lightweight synthetic mesh. 

Waterproof hiking boots transmit evaporated moisture vapor ("breathe") through their waterproof-breathable membranes when the heat and humidity are greater inside the boot than outside the boot. This works because warm, humid air naturally moves toward cooler, less humid air. It's this pressure differential, or heat and humidity differential, that effects evaporative transfer through seemingly solid materials, such as waterproof-breathable membranes.

Breathability mostly hinges on how much heat and moisture vapor hikers generate—based on their exertion levels, body chemistry, and the difficulty of their hikes—and on the heat and humidity in the outside air. Since breathability requires heat/humidity differentials, waterproof-breathable membranes work best 

Breathability will be limited or non-existent

Waterproof hiking boots typically breathe pretty well because the air around our feet will be warmer and wetter than the atmosphere outside our boots and shoes. However, more extreme environments (e.g. jungles, coastal rain forests, Alaska) and high-exertion hikes (2,000 mile thru-hikes, 20 mile days) may expose the reduced breathability of waterproof hiking boots and shoes. 

* The most uncomfortably warm I've ever been in a waterproof hiking boot has been walking around a store before/after a hike or wearing them casually around the house. 

Are waterproof hiking boots really breathable?

Scientific testing shows that most waterproof hiking boots are breathable—in spite of what many bloggers claim (as they mix up breathability with ventilation, air permeability, and/or moisture-wicking). 

Materials scientists, product engineers, and third-party labs measure breathability two ways. Some use tests that measure how many grams of evaporated water pass through a waterproof-breathable membrane over 24 hours. Some brands, such as GORE-TEX, measure Thermal Evaporative Resistance, or RET—how much materials restrict evaporated moisture from passing through them. The lower the RET rating (less resistance to evaporative transfer), the higher the breathability. 

According to Jonathon Swegle—the engineer who tests all the boots and shoes that apply for GORE-TEX waterproofing*—upper materials (such as synthetic mesh) have little impact on breathability. Instead, it's a series of small design choices—such as tongue design, adhesive and insole materials, TPU overlays, etc.—that mostly determine how much heat and moisture vapor pass through a hiking boot and shoe, waterproof or not. 

In his words, virtually all of today's hiking boots and shoes have breathable uppers. Synthetic mesh is breathable, but so is suede, nubuck leather, and (unless excessively treated) full-grain leather. (If you've ever seen steam rising off the back of a buffalo or cow in cool weather, you've witnessed the natural breathability of leather.)

* Since GORE-TEX is guaranteed for life, GORE won't provide waterproof membranes to any company until their boots/shoes test at or above GORE's required specs. Based on this testing, GORE may require specific design or materials changes to a boot or shoe before sourcing GTX membranes (and then re-testing the GTX boot/shoe for quality control). 

Socks and breathability

Socks also impact breathability. In my experience, my choice of socks actually matters more than my choice between waterproof and non-waterproof footwear when it comes to moderating my feet's moisture and temperature. 

Cotton socks, for example, absorb a ton of sweat and water—which not only feels gross and encourages blisters, but also reduces breathability. Merino blend or moisture-wicking synthetic socks, on the other hand, support breathablity by increasing evaporation. 

Sock weight also makes a difference. In my experience, switching from a midweight to lightweight merino-blend sock has more of an effect on my feet than switching from waterproof or non-waterproof footwear. I'll almost always wear lightweight merino blend socks in warm weather and either lightweight or midweight merino wool socks in winter to moderate the moisture and temperature around my hiking feet. 

Are waterproof hiking boots less breathable than non-waterproof?

Waterproof hiking boots are usually (but not always) less breathable than their non-waterproof counterparts. This has more to do with the added lining, backing, and adhesives than the waterproof membrane itself. 

Honestly, the average day hiker probably doesn't hike fast enough or far enough to notice this difference in nice weather. If I'm only hiking 6-7 miles, for example, I consciously need to focus on my feet (instead of my hike) to notice they may be slightly (maybe 10%) warmer or damper in waterproof footwear. My socks will be damp in either waterproof or non-waterproof footwear. 

When I ratchet up my day hikes to 12-18 miles, my feet may generate more heat and moisture vapor than my waterproof hiking boots can release. That's even more true of 15-20 mile backpacking days, where the added weight burns even more calories (heat).

In these use cases, long-distance day hikers and backpackers may prefer more ventilated and quick-drying trail running shoes to keep their feet cooler, trap less liquid, and speed up drying times. That being said, my non-waterproof trail running shoes will still be damp the morning after a hard day of backpacking—just slightly drier than my waterproof hiking boots.

The difference in breathability is more noticeable in winter—when my feet will be colder in non-waterproof footwear.

conclusion

Waterproof hiking boots aren't perfect. Thru-hikers, backpacking guides, and hardcore day hikers may have legitimate concerns about waterproofing or breathability coming up short—especially on all-day hikes in hot and humid weather. For them, non-waterproof trail running shoes may be the lesser of two evils.

That being said, waterproof hiking boots often work well for the average hiker. Most hikers are most active in nice weather and don't hike fast enough or far enough to have issues with the waterproof-breathable membranes failing them.

That being said, waterproof membranes aren't created equally. Hiking boots and shoes with GORE-TEX or eVent membranes generally will be more durable and breathable than waterproof hiking boots and hiking shoes that use brands' own proprietary membranes. Here are Hiking Feet's recommendations for the best waterproof hiking boots. 

The choice is up to you—hike your own hike!

My hope, though, is that this post has debunked some common myths and misunderstandings about waterproofing and (especially) breathability to help you figure out what makes the most sense for where you hike, when you hike, and how you hike. As with most outdoor gear decisions, your best choice boils down to your body and the specific kinds of hiking you do.