The 10 Essentials For Women in the Outdoors: Essential #9: Hydration


-Benjamin Franklin

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 Water is an essential element of life; everything living species needs water to survive. The average human body is made up of 50-65% of water and water covers 71% of the earth’s surface. As humans, we are supposed to drink at least 2 liters of water per day however the average American consumes 0.5 liters of water a day. The majority of us also do not consume enough water while out on the trails. If you’re actively hiking, it’s good to drink about 1 liter (32 ounces) of water every two hours. You might need more or less depending on the temperature, humidity and body weight, but that’s a good estimate of what you’ll need to carry if you can’t refill on your route. So on a 10-mile hike (assuming you hike an average speed of 2mph), you will need 2.5 liters of water.

For those of us who struggle with numbers:

10 miles/2mph =5 hours/2 =2.5 liters

How much does water weigh?

1 liter of water = 1kilogram = 2.2 pounds



For those of us who endure long hikes and enjoy backpacking, its extremely impractical to carry enough water for 20 miles or longer, assuming there is a water source on the trail; treating or filtering your water is the way to go. Before planning a long hike or a backpacking trip, always check the water sources in the area. Where are they located in relation to the trail? Are they accessible? Is it standing water or moving water? Is the water source completely dried up or plentiful?

Once you have established that there is an adequate and accessible water source where you are planning to adventure, you have the option of filtering your water and treating your water. So what’s the difference?


What’s the difference between a backpacking water filter and water purifier?

Simply put, the main difference lies in the level of protection they provide. Generally speaking, a water filter is designed to remove waterborne protozoa and bacteria, but not viruses. A water purifier is designed to combat all three classes of microbes, including viruses. Viruses are too small for water filters to catch and therefore water purification methods (UV light, chemical purification treatments, boiling water and mechanical pump purifiers) are used in areas where human traffic is high (popular campsites) and sanitation infrastructure is poor (developing countries).

The culprits: primary types of waterborne pathogens

Any water source on Earth could contain microscopic pathogens. Ingesting as few as 10 disease-causing microorganisms is enough to produce diarrhea and other dehydration-inducing symptoms. Pathogens, some of which can survive for months outdoors, fall within three primary types:

Protozoa include Cryptosporidium parvum and Giardia lamblia. These have a hard outer cyst that protects them against certain chemicals. Their relatively large size, though, makes them easier to filter out of water.

Bacteria include Escherichia coli (E. coli), Salmonella, Campylobacter and many others. Water filters can also remove these midsize microorganisms.

Viruses include Hepatitis A, rotavirus, and norovirus. Because they are smaller than protozoa and bacteria, they are difficult to filter out of water. Technically speaking, treating water by removing or neutralizing them is when you’re “purifying” water.


When should I use a filter?

If you’re traveling in the backcountries of the U.S. and Canada, a water filter, or more accurately a “microfilter,” is considered sufficient protection. In these pristine landscapes, where human traffic is relatively low, protozoa and bacteria are considered the main threats.

Examples of microfilters:

Sawyer squeeze water filter system Great for individual, on the go, use.

KATADYN BeFree collapsible water bottle filter Great for individual, on the go, use. I just purchased this filter and I am excited to use it.

MSR MiniWorks EX water filter Pump filter system for individual use

MSR Trail Base gravity filter system Gravity filter great for large groups

Platypus Gravity Works filter system Gravity filter great for large groups

Lifestraw Play Filter water bottle Great for individual use, all in one bottle and filter

 When should I use a purifier?

If you’re traveling to less-developed countries, where water treatment and sanitation infrastructure is poor and/or people don’t practice good hygiene near water supplies, a water purifier is the safer option.

Examples of purifiers:

SteriPEN Ultra water purifier Uses UV light to denature pathogens

MSR Miniworks EX purifying system Filter pump and chemical tablets

KATADYN chlorine tablets Wait time is 4 hours. I use these for internationally traveling because they are lightweight, simple and cheap

Potable Aqua Iodine tablets Wait time is 30 minutes. I have been using these for years and they are my backup purification system. They are cheap, lightweight and easy.

Tip: Always carry a backup treatment system. A filter can be lost; batteries can drain; a device can get broken. Chemicals (Iodine or chlorine tablets) offer extra security with negligible weight. Boiling is a surefire backup option: Bring water to a rolling boil for 1 minute, or for 3 minutes if you’re above 6,500 feet. Chlorine tablets are more effective than iodine pills because they protect against Cryptosporidium parvum.

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The 101 of gathering water

The where…

  •  Flowing water, especially in a stream or river. This is a good option because it isn’t conducive to the growth of algae or the accumulation of microorganisms. A bonus is that mosquitoes don’t lay eggs in fast-flowing water.
  •  If no clear flowing source is available, then look for calm water (a lake, a pool, a slow-moving stream) without a lot of sediment or silt. Clearer water passes through a filter more swiftly and reduces the chance of clogging.
  • A location that allows you to reach well away from the shore, where microorganisms tend to accumulate in higher concentrations.

What to avoid…

  • Water (particularly at lower elevations) near meadows or pastures where animals have grazed or near popular, established campsites.
  • Evidence of pack animal traffic or other domesticated animal activity.
  • Signs of sloppy human behavior or a prolonged human visit.
  • Excessive amounts of foam or brown scum, which can indicate algae blooms; though algae itself is rarely harmful, it indicates a nutrient-rich environment for microorganisms to grow.
  • Dirty snow, which indicates human visitors and impacts; also, don’t assume that even clean-looking snow is “safe” because bacteria can live for months in ice.
  •  If murky or silty water is unavoidable, gather from the surface and let the pot sit so the sediment sinks to the bottom.

Leave No Trace Practices

  • Good practices are required to keep water sources pristine. As more and more of us visit wild places, we need to rededicate ourselves to Leave No Trace principles. Below are some of the key principles related to preserving the quality of backcountry water:
  • Camp at least 200 feet away from water sources.
  • Properly dispose of human waste at least 200 feet away from water sources.
  • Carry water for cleaning at least 200 feet away from water sources.
  • Never use or toss soapy water directly into backcountry water sources. It can help spawn a population of microscopic pathogens in the water.
  •  Dispose of soapy water by dispersing it on soil rather than rocks. Soil microorganisms help metabolize the pollutants.


  • Backpacking in Washington’s North Cascades National Park: Microfilter
  • Camping on a holiday weekend at very popular lowland lake: Purifying agent
  • Hotel stay in Peru: Purifying agent
  • A quick method for domestic use: Microfilter
  • A quick method for international use: An ultraviolet light purifier like the SteriPEN. Caution: This handheld device works best in relatively clear water (strain with a bandana first if it's not) and requires batteries (pack spares).
  • The lightest possible treatment: Chlorine dioxide tablets
  • The best method for silty water: Good old-fashioned boiling works everywhere, but it's perfect for ultra cloudy rivers and sediment-choked puddles.
  • An easy, speedy method: Pump filters use microscopic pores (.2 microns or less) to snag bacteria and protozoa while allowing water to flow through the filter at one to three liters per minute.
  •  A hassle-free method for big groups: Gravity filters are quick and trap everything a pump model does, but handle larger volumes of water.

Thanks for reading and see you on the trails,