Not Quite the Holy Grayl of Water Purification

I really wanted to love it, I even stood up for it on Back Country Post Forums, before given it a real test. The Grayl Ultralight is a new water filter and purifier that works almost like a coffee press. For a quick and dirty of how it works check out their video (Or read my first impressions here):

The Grayl Ultralight intrigued me and I was excited that Grayl was gracious enough to give me a free purifier to test 6 days on the High Sierra Trail to Mt Whitney. Before I got out on the trail, I did some in home tests and it worked great. It was simple, sturdy and filtered water quickly and easily. My first impressions of the Grayl Ultralight were superb!

But then I took it out on the trail, and filtered water from creeks, rivers, and Mt Lakes. Now all of these water sources on this trip were not very silty and the water was very clear. Unlike my Grand Canyon trip where I was filtering water from the silty Colorado River.  Basically all the water sources I hit on the High Sierra Trail should not have been to difficult for any water filter to cut through.

I used the Grayl Ultralight for myself and a friend, as our only water purification means for 6 days, 5 nights. The Grayl started off great, it worked just liked it worked on the tap water in my apartment that I tested it on. On the second day we filtered some water from a stream and had no issues topping off a couple Nalgenes.

On the 3rd day we were pretty low on water, and had to fill both our camelbaks (3 liters each)  and water bottles. This is where things started to go down hill.

We stopped at Hamilton Lakes, a beautiful stop on the way to the Kaweah Gap. I was excited to really test out my Grayl and see what it could do, so I dipped it into Hamilton Lake.

Grayl Ultralight

So lets take a look at what topping off all my water sources in one go with the Grayl Ultralight.

  • One Press of the Grayl Ultralight = 16oz of clean water.
  • 1 liter = 33.8oz
  • 3 liter (1 Camelbak) = 101.44oz
  • 1 Camelback = 6.34 Grayl Ultralight fills

Based on the above math, I had to fill and press 6.34 times to fill my Camelbak, thats not including my water bottles,  my buddies Camelbak etc.

It started out fine, the Grayl worked great, but each press became just a tad bit harder then the previous one. Each press took just a little bit more effort to press.

Grayl Ultralight

The more and more water I pressed and purified, the more I found myself concentrating my pressing form. You can see in the above picture I am pretty much just using my arms and shoulders, this is fairly early in the trip. The more and more I used it the more, I would find myself focusing more and more on putting all my body weight over Grayl. Toward the end of our water resupply at Hamilton Lake, my hands were sore as hell. The rim of the Grayl is hard and if you use it multiple times back to back your hands will be in some pain.

The Hamilton Lakes stop, was not completely horrible for water purification but my hands ached at the end of it, and I was glad to be done filtering water for the day. It just wasn’t exactly an enjoyable experience. But I had clean great tasting water!

The next day we camped high in Kaweah Gap, and it wasn’t until the next day that we filtered water again. The more and more we hiked on the more I slowly began to hate filtering water. It became harder and harder to press down, and my hands hurt more and more.

By day 3 I started to wear gloves while filtering water my water with the Grayl Ultralight. The gloves helped ease some of the pain on my hands, but still it became tougher and tougher to purify our water.

I began not topping off my water sources, because I just hated filtering water at this point. I then resorted to extreme measures to same my hands, I resorted to my trusty Ka-bar!

First off, I do not recommend what I am about to describe, but its what I decided to do, in order to continue to filter water more easily. I put the blade of my Ka-bar across the top of the Grayl and put one hands palm across the top of the blade and the other on the handle of the Ka-bar. I then pushed and twisted, and it seemed to go down a little bit easier.

The filter on the Grayl Ultralight seemed to get clogged extremely quickly. It made filtering water a chore, something I loathed doing every day on the trip. The bottom line is that the Grayl was the least enjoyable piece of gear that I brought on the trip.

I wanted in the worst way to enjoy the Gray, I really did give it a chance. I loved its design, simplicity and strength. But the amount of physical effort it took to get clean water, was just not worth the squeeze.

Its a lot more expensive but I am now looking into the MSR Guardian for future trip, as it is self cleaning.



High Sierra Trail to Mt Whitney: Day 6


2016 All Star Game and Home Run Derby


  1. John

    You and your friend should have taken turns or concentrated on filling your own bottles and camelbacks.

  2. Visitor

    Were you pressing directly on the drinking/mouthpiece rim, or directly onto the cap? If you leave the cap on, but unscrewed just a bit (so air can get through), it’s a lot easier. Don’t press directly on the clip loop, but on the rim of the cap. It doesn’t seem to do any damage, and it’s much more comfortable.

    • Mike

      I tried using the cap to push down also, no luck to make it any easier after a couple day on the trail.

  3. P

    From what I’ve heard, you’re supposed to leave the cap off when pressing. Is it possible to try it that way?

    • Mike

      I did take the cap off while using it, that is why my hands hurt so much pressing down. The rim was cutting into them as it became hard to press.

  4. Dale H.

    Thanks for the info. I was seriously looking into one but our water sources are really murky and lots of sediment.

  5. Jeremy

    After using the Grayl I would have to agree with Mike….
    Avoid buying, as both my filters only last ~20L (NOT 150L)
    I bought mine and a extra filter for travelling to Peru. I wanted a filter that kept out Viruses as my daughter is Type 1 Diabetes. I tried it out on a weekend trip in the Bugaboo Provincial park. I filtered 10L of crystal clear Glacier water. But the filter had already started to slow.

    Next was the trip to Peru. Used it in the airports trip water was “pre-filtered” by the adventure company, but travelling with a type 1 diabetic child we did not want to risk getting sick in the middle of no where. The filter stopped after ~ 8 more litre., The last try was painful and took about 1.5 min to filter.

    Second filter waited to use for the Inca Trail. Did not fair better, slow after 5L and useless after 15 litres.

    Wish I found Mike’s post before I bought!

    Very disappointed and cannot recommend to anyone to buy, unless you enjoy spending a lot of money on filters, as these filters cannot be back flushed.

    • Mike

      Sorry to hear you had the same experience. I was kinda hoping I just had a bad one, but honestly didn’t want to risk taking another on a second trip…

      What other filters are you looking at now?

  6. Duane

    Same issue here unfortunately… I only got 6 days out of mine (4 days of filtering melted snow and and 2 days of clean streams) so i can’t justify buying another filter at that rate.
    I’m going to pull the filter apart and check what I presume is mostly paper/carbon in which case backflushing is of no use to prolong the life… once the carbon does it’s job it’s a throw away if I’m not mistaken.
    A total bust as far as I’m concerned
    A real Shame.

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