Not Quite the Holy Grayl of Water Purification

Update: Cattywampur is  in transition to a new website Called Seek Adventure (, you can finish reading this article and join the discussion on Grayl at the new Seek Adventure Forums!


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.

Join the DIscussion on Grayl at the Seek Adventure Forums!



High Sierra Trail to Mt Whitney: Day 6


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  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.

  7. David Riddel

    Perhaps 15 litres of mountain streams over 3 days before I was looking at other options. ‘300 uses’ might be for filter functional performance, but not useability…. and I weigh 94kg, so I have a lot of body weight to apply. My last usage was pressing on the open top with a clean, flat river stone to reduce the pain in my hands.

    • Mike

      River stone was probably a lot safer than my knife lol, smart move.

  8. Linda

    Same issue here. First 6 uses great, that’s filtering municipal tap water, now sitting on it to press it and getting nowhere. Very frustrating at start of 1 month camping trip! Have emailed Grayl for help, awaiting reply.

  9. Catherine

    How is their return policy? Seems that if it doesn’t work as advertised, they should take it back.

  10. JR

    Im sorry you all have had these experiences, i love using my filter – I also disagree with some of the assumptions around whether its effective or not. Unless your water is coming out visibly contaminated, or you are taking samples of purified water to be tested, any claim that your filter isn’t working even when its difficult to press really doesn’t mean much (after using the current filter in my bottle a little more, i do intend to try this myself to know for sure).

    Granted, I absolutely agree with the fact that it does become difficult to press after a point, even though this is subjective too – How you use the filter of course depends on your environment and setting – im relatively light at around 150 ilbs so it didn’t take for pressing to become difficult. My solution? I started wiping off the pants on either side of my butt and simply sat on it – works like a charm for me, no hurt hands, and instead of wrestling with the damn thing, i can take a moment to rest.

    • Mike

      At no point have a had any assumption that my water was not pure. I definitely believe it works, its just not an easy filter to use and I do not recommend it for long backpacking trips.

  11. Gehno

    Sound like a real [censored]. I’ve used mine for a year now and never had one problem. I think the lid was on to tight. THE SYSTEM WORKS BY REPLACEING THE AIR WITH WATER., THE AIR MUST GO SOMEWHERE. LOOSEN THE CAP AND STOP BEING SUCH A [censored].

    • Mike

      I censored the not so nice words out of your comment…. If you read the previous comments I did not have the lid on and I fully understand how this filter is supposed to work.

      If you would like to discuss further I would recommend you jump here:

      Because this website will be shutting down eventually. I would love to know what kind of trips/water sources you have filtered from in over your year of use?

      • Jeremy

        @Genho. Wow you have a strong opinion. One I have not seen anywhere else on the net! Wonder what company you work for?

        At any rate. This product was garbage. The store I bought it through now won’t carry the product from all the returns….coincidence? I think not

  12. Kevin

    Damn I just ordered one of these so I hope I don’t have your experience. I’ve read a lot of other people that claim they’ve been using theirs for a long time and have even bought a second one and they’re happy with them. I don’t think it had anything to do with your issue but Grayl says to leave the lid on a quarter turn open so you have more support for your hands and help prevent contamination but don’t create an air seal.

    • Mike

      I hope you have a better experience too! Please let us know after you test yours out for a few trips over on our new website Seek Adventure

  13. Everet

    This thing is just play hard to use. I bought three about 3 months ago in preparation for a 4 day/3 night trip to King’s Peak in Utah (three in our group). We tested them with regular tap water at home a few times between the purchase and the hike and each test became progressively harder to press the filter. Before leaving on our hike, we had put 3 liters through each one and I noticed it got more difficult with each try. But, we decided to take them on our hike anyway. We just got back from the hike and we all agree the hardest part of our trip was filtering the water. I have not concerns about the purity of the water. But is was very annoying to have to work so hard to get two liters of water. I’m planning to return them and ask for my money back. Unless someone can offer a solution for solving the problem.

  14. Blair deLaubenfels

    I used mine 4 times before it clogged up at the worst moment, on my trip to India. I tried it with and without the cap on and it just spilled water out the sides. I really, really wanted this to work, but $60 for less than a quart of water total was a big rip off.

    • Mike

      Thanks for sharing your experience! Unfortunately, Cattywampur is closing down soon, all the articles and discussions have been moved to our new website at please come by and join the conversations!

  15. Brandon Thompson

    Appreciate your and everyone’s else’s experience. I’ll have to pass on it and this brings me up to a second topic.
    Always have a back up. What if for some reason it dislodged from your back pack and tumbled down a cliff. Stopped working. Plastic breaks …Etc.
    Some purification tablets and maybe simple carbon paper filter (not ideal) along those lines to get you through. If I need back up for anything it would be water. Screw the extra weight.

    • Mike

      My back up is usually boiling water. If it’s silty I let it sit for 24 hours and skim off the top then boil. This blog is about to close down, feel free to join us on to continue the discussion!

  16. I don’t see anybody in pictures or video pre-filtering with the the Grayl. Why is this? As I understand it, no matter what kind of filtration or purification used it is always proper protocol to pre-filter.
    One if the weirdest things about the advertising of this product is the absence of pre-filtering.
    Did you pre-filter with a bandana or something?
    I am interested to know.

    Thanks for your review.

    • Mike

      I did not pre-filter with a bandanna or anything else for that matter. I was also filtering from crystal clear snowmelt lakes…. There was not much if any sediment.

      Feel free to continue the conversation on our new site as this one will shut down shortly. Check out

  17. Rick

    I was an early adopter of the grayl, when there was only one stainless option about 4 years ago. I had some qc issues with one of them (the lid was bent somehow), and so they sent me another one. The only reason I had gotten it was for its virus filtering ability. My only concern was that given the nominal size of viruses, the travel filter had no indicator that it had to be replaced, as it wasnt a standard pore filter.

    I had never intended to use it myself as a “outdoor” filter- rather as a filter where I could fill up while traveling so that viruses would be removed from tap water, should it be present (i.e. mexico, cambodia, etc).

    Its fills a niche, but I think outdoor hiking is beyond its capability, and there are plenty of other filters out there that work better, if you don’t need to worry about viruses. If you do, your choices are much fewer and far inbetween. I wen’t guardian, but sometimes it will also be a sawyer mini with a MSR MIOX.

    MIOX is the only thing that can offer some residual protection of the water- and the ability to disinfect contact areas, if you can put up with the wait time.

    • Mike

      Very valid point, possibly a good filter but just not for the backpacking use case!

      Feel free to continue the discussion on our new website because this website will be shutting down shortly!

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