Do I Need to Filter My Water on the PCT?

Hikers gathering water on the PCT. Photo by: Malin Klingsell

Hikers gathering water on the PCT. Photo by: Malin Klingsell

In your quest for an ever-lighter pack, have you pondered tossing your water purification system to the curb to cut the last few ounces from your base weight? Are you enamored by super-hikers who brag about their six-pound packs? Or by hikers who casually gulp from groundwater without breaking stride? Maybe you can be one of those ultralight gods as well. Just take the plunge. So, with the promise of an ever lighter and more comfortable pack, you ask:

“Do I need to filter my water on the PCT?”

High-traffic areas and isolated cases may not be safe to drink untreated, but a recent article in Slate examines this popularly held belief and found most backcountry water to be safe to drink. Photo by: Malin Klingsell

High-traffic areas and isolated cases may not be safe to drink untreated, but a recent article in Slate examines this popularly held belief and found most backcountry water to be safe to drink. Photo by: Malin Klingsell

No. Technically you don’t need to filter your water while hiking the PCT. I spoke with many hikers who didn’t filter water the entire trail and they reported no problems. Many elite or professional—is that a thing? Professional hikers? Anyway, many of these extreme ultralight hikers don’t want to hassle with the extra weight of a filter or the time it takes to actually filter the water. And this decision seems to be backed up by science. A recent article in Slate examined the quality of backcountry water and found it to be surprisingly clean. It seems most episodes of giardiasis are driven more by poor hygiene and less by contaminated water.

And here is the rub: The water is largely fine out in the woods. However it becomes more risky for humans when there are humans around. A water source at a highly used campsite may have a much higher risk of contamination than a stream miles from where humans are eating, sleeping, and pooping.  Additionally, when traveling where others have been prior, one should consider how much they trust previous visitors to have exercised proper backcountry bathroom etiquette. Did everyone make sure their cat holes were 150 feet from the trail and water? Did they bury it, or leave it on the surface possibly beneath a stone? These corner-cutting decisions lead to human-contaminated water. This is why I feel the question really ought to be:

“Should I filter my water on the PCT?”

And here is where I can confidently say, “Yes.” There are many situations where one can successfully argue that filtering isn’t necessary: melting fresh virgin snow in the Sierras, for example. However for the vast majority of water sources you’ll encounter on the PCT, there just isn’t any way to be 100% sure that there isn’t some form of contamination—a dead animal trapped upstream, or livestock using land that drains into the watershed. It’s not that backpacking without a filter is wrong or impossible, but that it’s simply more challenging.

Let’s consider what happens when you come in contact with a contaminant like Giardia: Several days after contact you’ll begin to experience severe cramping, bloating, and diarrhea. You may feel feverish. Because you’re not absorbing the liquid from your stool, you’ll become weak. Then you’ll become dehydrated. If you’re not able to reverse the symptoms, you’ll have to leave the trail to get an antibiotic. It could take 2-6 weeks to fully recover. During this time, your body will have lost its conditioning, atrophied, and any friends you were hiking with will be long gone. Spend too much time off-trail and you may miss your Washington weather window, or worse: You may be tempted to give up entirely.

When faced with the choice of hauling a three ounce filter and spending about 15-20 minutes per day (total) dealing with filtering water, for me it becomes a clear decision: The risk of not filtering is simply not worth the reward—for me personally. But HYOH. If you ditched your filter so you can set the land speed record on the PCT next year, then more power to you.  The explosive diarrhea should actually work to your advantage, propelling you forward with each bout.


This topic is becoming more popular on trail, so I’ve anticipated the heckling, and responded ahead of time:

But I could use tablets or drops, right? Those are lighter than a Sawyer.

Yes, you could. But I don’t. Here’s why: Consumables require attention and planning. It’s minor, but the stress of planning consumable treatment resupply is one more thing your mind has to keep track of. With a filter I don’t have to think about how many drops or tablets I’ll need here or there on the trail. But do what you find works best for you, Squirt.

But squeezing a Sawyer takes lots of time, and the bags always break.

There I am on Day 2 of the PCT with my shiny gravity filter. Couldn't walk with it, and hanging it was a pain. Learn from my mistakes. Less is more.

Yes, squeezing the water through a Sawyer takes time and bladders do fail eventually. However, rarely did stopping to filter water annoy me. I broke two Evernew bladders on the trail. One I dropped, and the other I skewered with a yucca leaf. Both were in the first month and due to carelessness. Afterward I had no problems. I suggest preemptively replacing bladders every third of the hike. It’s a bit pricey, but on the upside, you’ll have some gently used spares at home.

I'm all clever and am going to use a gravity filter.

So was I. Well before the Sierras I decided it not worth the weight and hassle. I found I was spending more time looking for suitable spots to hang the system than it took to fill the bottles by squeezing. All the biners, fittings, hose lengths and mesh storage pouch were just more crap parts to keep track of. Now I just use the Sawyer squeeze and the little blue cleaning collar to help me not spill.

Can't I just thread my Sawyer onto my Smartwater bottle and squeeze the bottle?

Yes, but the more you crinkle the bottle the shorter it lasts and less water it carries. Many hikers used this approach and I tried it briefly before determining it too be a little too ‘hiker trashy’ for myself.

Can't I take the Sawyer mini? It's lighter!

It is, but unless you are planning to run it as an inline filter through your camelbak (or equivalent) then I would advise against it. You will need more elbow grease and patience to squeeze water through the mini. Most thru hikers choose the squeeze for this reason.

But the what about the Katadyn BeFree?

Yes, this is the new hotness that everyone is talking about. Here are my thoughts, never having used it yet:


  • Easy to clean: just rinse filter in clean water

  • Easy to pack, bottle collapses and takes less space as it empties

  • Simple, all-in-one solution

  • Efficient for refilling - fill-and-go


  • Floppy when partially full

  • Flexible bottle is more prone to failure (it is a bladder after all)

  • Filter cap is not compatible with other containers that I carry - no back-up if BeFree bladder fails

  • It may be difficult to pour into the rehydration pouches for meals

  • Bladder may be difficult to fill without a scoop

  • Filter needs replacement much more quickly than Sawyer squeeze (Sawyer is good for 100,000 liters; Katadyn recommends replacing the BeFree filter after only 1000 liters.



I believe the argument for filtering water is pretty compelling. It boils down to the risk just not being worth the reward. However, as I mentioned, this is largely personal preference. Many hikers get by with no filter—but they must be much more careful when sourcing water and predicting their needs in various conditions since some sources may be too nasty to draw and drink unfiltered.

I know there are a variety of opinions on this issue, and we would all benefit from first-hand experiences on this topic. Share your stories in the comments!


A warm thank you to Malin Klingsell who provided photography for this article. Malin hiked the PCT in 2017, is a vegan, and is an amazing photographer. She blogs at and has a kick-ass instagram @friluftsvegan.

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