Treating Water and Managing Hydration on the Appalachian Trail

Water is the most important resource thru-hikers must learn to manage on the Appalachian Trail. Water is typically easy to find—as hikers meander through the woods they’ll cross numerous fresh springs, streams, ponds, rivers, and lakes from which they can draw water. It is not uncommon for hikers to pass multiple water sources in a single day. Shelters and popular campsites are also usually positioned within reach of a water source. Guidebooks, apps, and some maps will mark the locations of viable water sources for hikers to take advantage of.

It is important to note that water sources listed on maps or guidebooks can sometimes dry out in drought conditions. Local climate and weather conditions can affect the availability of water on certain areas of the trail (we’re looking at you, Pennsylvania in July). If there is an area displaying uncommonly low water levels, local rangers and trail clubs might post alerts to keep hikers informed. Be sure to stay prepared in case of dried-up sources, and don’t rely on other people or organizations to keep you up to date.

How Much Should I Carry?

Photo: Nadine Symons

The amount of water hikers need to carry at a time depends primarily on the number of water sources available on a given day. Crossing fewer water sources necessitates carrying greater amounts. However, if water is abundant on a section of trail, it becomes more a matter of personal preference.

Water is one of the heaviest items hikers have to carry, weighing approximately 2.2 pounds per liter. As a result, carrying more than is needed can really weigh you down. A general estimate is that hikers will have to carry anywhere between 1-2 liters of water. It’s unlikely most hikers need to carry more than 2 liters at a time, except in special circumstances.

Hikers new to the trail will likely need more water than seasoned backpackers until their bodies adapt to the trail. Even so, new hikers still tend to carry more water than is necessary. With time every hiker will begin to identify their hiking preferences and find their preferred method for handling their water needs.

That said, thru-hikers often suffer from chronic dehydration due to the high levels of activity exerted every day. It simply becomes more difficult to sufficiently drink enough to water stay well-hydrated in these conditions. If you feel thirsty, it usually means you are already dehydrated. It is best for hikers to continually drink water throughout the day, particularly in warmer weather, to help avoid more serious health complications associated with dehydration. Drinking a full bottle at each source is a good rule of thumb for staying ahead of dehydration.

Water Treatment


With any open backcountry water source there is an inherent risk of contamination. The water found along the AT is likely not swimming with parasites, but the obvious problem with viruses and microscopic organisms is that you can’t tell if they’re there just by looking. When most people speak of water-borne illness on the AT they are likely referring to Giardia: a microscopic parasite that can cause severe nausea and diarrhea among other symptoms.

It is highly recommended that all hikers carry with them some form of water treatment method. These typically come in the form of a filter or chemical treatment. Both methods are effective and are much more enticing than boiling your water one pot at a time.


  • Most popular models include Sawyer Squeeze and Katadyn BeFree.
  • Preventative measure: filters out particulates and pathogens from collected water.
  • Usually requires more physical effort in the form of pumping or squeezing.
  • Water is drinkable immediately after it’s filtered.
  • May require regular maintenance to maintain effective functionality.

Chemical Treatments

  • Most common types are chlorine drops, iodine tablets, or Aquamira.
  • Reactive measure: kills pathogens in collected water through chemical reactions.
  • Typically lighter.
  • Does not keep particulates out of water.
  • Usually requires time to fully treat water before drinking. Typically 10-30 minutes depending on the amount of water being treated.

While these are not the only methods for water treatment, they are the most popular. UV light wands are effective but rely on batteries or regular charging in towns. Some hikers prefer the low-tech solution of adding chlorine bleach to their water. However, this method is not recommended. If done improperly it runs the risk of being toxic to the drinker.

Drinking unfiltered/untreated water does not guarantee you will become ill. There are hikers every year who travel the trail, never treat their water, and don’t get sick. Some of these hikers may have adapted resistances to certain infections or may actually have a more robust immune system, but most are simply just lucky.

Treating water can become a tedious camp chore, prompting many hikers to try unfiltered water to save time and energy. Much of the time you may squeak by, but it only takes one time to put you in a world of discomfort. Even so, should you run into a situation when you need water and are unable to access a recommended treatment method (or if you’re just being complacent) you can sometimes determine the level of risk a water source poses by a number of objective factors listed below.

  • Giardia is a parasite that lives in the guts of people and animals passing via feces. Though all backcountry water sources may potentially harboring Giardia cysts, lower-lying water sources near farmland or in areas with higher access to animals and runoff pose a greater risk of contamination.
  • Water-borne pathogens tend to attach themselves to suspended solids and other floating particles present in the water as opposed to just swimming around freely in the liquid. The less dirt and particles in your water the less likely it’s going to make you sick. Granted, this is very much a “rule of thumb” estimation.
  • Drawing from a flowing, moving water source is always better than drawing from still water. Still water runs the risk of stagnation and is more likely to contain parasites and waterborne illnesses.


Should You Treat Backcountry Water? What the Science Says.

Water Treatments for Backpacking and Hiking

How to Survive Waterborne Diseases on the AT

Featured image via Steve Gallagher


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Comments 4

  • Cosmo Catalano : Feb 15th

    I suspect the most likely route for pathogens is from cross contamination when treating water. Any number of times I’ve seen untreated water dripping down the sides of a bottle or squeeze bag and over the outside of a filter onto the “clean” water bottle you will be drinking from. Pretty easy for it to get from there to your mouth. Hikers would do well to set up a consistent method of manipulating their treatment system that reduces the chances of cross contamination. Want to practice? Filter water out of your toilet bowl a few times and see how you feel about drinking the result….

  • Nate - Day Hiker : Feb 15th

    When I started my thru-hike last year, I pretty much always left a water source with two liters of water. After a month or so on trail, I dropped that down to one and just drank a good bit at the water source to stock up before heading out. Then at my last water source of the day before camp, I would usually fill up both liter bottles and sometimes the Sawyer Squeeze bag so that I wouldn’t have to refill later that night or first thing in the morning depending on what the water profile looked like going forward.

    For filtration, Sawyer Squeeze the whole trip worked well for me. Replaced mine once in Erwin, TN, because I believe mine froze a couple times in the Smokies in the single digit temperatures. I filtered pretty much all my water except for when I got it from a spring high on the mountain while it was below freezing out because I didn’t want to freeze my filter and felt comfortable with the cleanliness of the water.


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