Dehydration is a quiet thief. It doesn't announce itself with a sudden jolt; it creeps in slowly, replacing clarity with confusion, strength with fatigue, and joy with a dull headache. I learned early on that without water, the most beautiful trail becomes the most challenging. That's why water—specifically the means to carry, filter, and purify it—is perhaps the most fundamental item on the list of the Ten Essentials of Hiking.
In my younger years, I relied solely on a few large bottles, hoping they would last. I quickly realized that hoping is not a strategy. The ability to source and treat water in the wilderness is a commitment to your health and safety. As we age and continue to pursue an active outdoor lifestyle, our bodies demand consistent hydration to maintain energy, lubricate joints, and regulate core temperature. Being water-wise is the key to enduring miles and truly enjoying every moment under the sun.
Here is a look at the essentials of water—quantity, containers, and purification—to ensure you stay strong and hydrated on every adventure.
Why Water is Non-Negotiable
Water makes up a great percentage of our body weight and is essential for every biological function.
- Preventing Heat Exhaustion. Proper hydration is critical for your body’s ability to sweat, which is its primary mechanism for cooling itself down. Without enough water, your risk of heat exhaustion and heat stroke increases dramatically.
- Mental Clarity. Dehydration impairs cognitive function, leading to poor decision-making and navigational errors—two things you absolutely want to avoid in the backcountry. And to multiple the risk, as we get older the part of our brain that tell us we are thirsty doesn’t work as well as it did when we were younger. So, older folks, don’t depend on the “feeling” of being thirsty.
- Sustained Energy. Water helps carry nutrients and oxygen to your muscles. Consistent drinking prevents muscle cramps and sustains the energy needed for long days of hiking.
Quantity and Carry: How Much and In What
The general rule is that a hiker should consume approximately half a liter (17 oz.) of water per hour of moderate hiking. However, this increases dramatically in heat, high altitude, or on steep terrain.
- Start with 2 Liters. Always start your hike with at least two liters (about 68 oz.) of water already in your pack. This is your immediate reserve. If you bring less you may run out quickly and/or you may need to stop more often at water sources to filter/treat more water.
- Reliable Containers.
- Disposable Plastic Bottles (e.g., SmartWater). These are popular among experienced hikers. They are lightweight, cheap, and easily fit most standard water filters. They are not the most durable, but they serve the purpose of minimal weight. Also consider the environmental impact of disposable water bottles. Disposable water bottles are a significant source of microplastics, with studies showing that a liter of bottled water can contain approximately 240,000 tiny plastic fragments, which are 10 to 100 times more than previous estimates. The production and disposal of these bottles contribute to widespread microplastic contamination in the environment and human bodies.
- Soft Flasks/Water Bladders. These are ideal for storing large quantities and placing weight closer to your back for balance. A bladder with a drinking tube encourages frequent, hands-free sipping, which is the best way to stay hydrated.
- Hard Bottles (e.g., Nalgene). Durable and reliable, they are great for mixing electrolyte drinks or using as a hot water bottle for warmth in a sleeping bag, though they are heavier. Lighter ones are now available that mimick the size of disposible plastic bottles, significantly reducing the environmental impact. Two popular choices are: CNOC Thru Bottle, NOBO Bottle by Igneous, and the M!GO Bottle from Mazama.
Purification: Making Wild Water Safe
Relying solely on carried water is often too heavy and impractical, especially on longer hikes. Knowing how to safely collect and treat water from natural sources is a key self-sufficiency skill. Never drink untreated water from a stream or lake—it can contain harmful bacteria, protozoa, and viruses.
1. Water Filters (Primary Method)
- How They Work. Filters physically strain water through tiny porous tubes, removing bacteria (like E. coli) and protozoa (Giardia). They are a quick and easy way of getting immediate drinkable water from most water sources in the wilderness.
- Best for. Most hiking and backpacking scenarios where water sources are plentiful.
- Types. Look for squeeze filters that attach directly to a soft flask or a disposable bottle, or pump filters for larger volumes. Look closely for filters with pore sizes of .1 microns; .2 micron filters, although faster, are not nearly as effective. Several of the more popular choices are: Sawyer Squeeze, Katadyn BeFree, and Membraine Solutions.
2. Chemical Purification (Backup Method)
- How They Work. Tablets (usually iodine or chlorine dioxide) kill viruses, bacteria, and protozoa through a chemical process.
- Best for. A backup method, especially where virus contamination is a risk (less common in North American wilderness, more so in international travel). They are extremely lightweight but require a wait time (usually 30 minutes to 4 hours) before the water is safe to drink. Aquatabs are one of the easiest options.
3. Boiling (Emergency Method)
- How It Works. Bringing water to a rolling boil for one minute (or three minutes at elevations above 6,500 feet) kills all pathogens (viruses, bacteria, and protozoa).
- Best for. A situation where your filter fails or you have run out of chemicals. It requires fuel (or a camp fire) and time, making it less practical for frequent use.
Carrying the means to treat water turns every stream into a hydration station. By embracing a smart hydration strategy—drinking regularly, carrying a sufficient reserve, and always having a means to filter and purify—you guarantee that your body is fully capable of enjoying the beautiful, active life you've chosen on the trail.