Advice please concerning water filtration systems

My granddaughter (23 ) loves travelling. She has already trekked through the High Andes to Machu Picau and two years ago joined a young persons camping tour from San Francisco to New Orleans. This trip covered stays in various of your National Parks, etc. She is most definitely a fan of your fabulous Country and has plans for more tours, treks, etc.across the USA.

Unfortunately she was diagnosed with a severe case of Ulcerative Colitis, an autoimmune disease, after her San Francisco/New Orleans trip. She picked up the ecoli bug and spent a night in hospital in Flagstaff, where she received excellent treatment. However on her return to the UK she was hospitalised and it was then they diagnosed Ulcerative Colitis. That was two years ago now and her condition has since been stabilised ( although is always subject to flare ups) and already is planning a trip later this year, but she has to be very careful with her health, especially drinking clean safe water on any trekking trips.

I am very much aware that backpacking and trekking in the great outdoors is very much a part of life in the USA, so I think you guys are the experts. I would like to buy her a water filtration system that is easy to carry/operate and minimises as many risks as possible. I have looked online but am confused by the variety of products available. However one system that does interest me is the Sawyer Mini Filtration System - MINI Water Filtration System | Sawyer Products

I would welcome any comments on this, or recommendation of any other suitable water filtration systems.

Thanks for your help


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This is very kind of you to do for her David. I’m certainly no expert, but have used a Sawyer many times and think they work great. For what you pay, I think they are very much worth while.

I know some people also really like the Steripen. A friend of mine from university will only use those. The only downside I personally have with them is the filtration aspect.

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I use (& swear by) my Sawyer Mini. Goes with me on every fishing trip.
I’m also not a doctor, so while I’d endorse the product, take the endorsement for what it’s worth… not much.

That said, I did happen to find this article interesting a few months ago.
I still bring my Saywer anyway.

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I am also can’t give you an opinion from rough earned person experience. However, things I have read that I should consider when choosing a water filter / purifier, and the two are not necessarily the same thing, I can pass on.

The fundamental thing to be decided is do you only need to filter out bacteria or do you also need to kill possible viruses in the water too?

The Sawyer is typical with a 0.1 micron filter, will keep out bacteria if used properly, It will not block viruses. Some people complain about the bags breaking. The newer ones were supposed to be better, but still I read complaints. I have the original bag, none have failed. Probably because I’m kind of whimpy guy with weak hands. I can’t squeeze the Sawyer Squeeze hard enough to burst the bag. :hushed:

A 0.1 micron filer will not filter out viruses as viruses are smaller than 0.1 micron.

A Steripen can kill viruses with UV light. but only if the water is clear. The uv wont kill viruses hiding behind something that blocks the light. The Steripen needs working batteries, and electronic gadgets break. (which worked out great for me, I made a living for more than 30 years fixing electronic things that stopped working) Possibly a problem in remote areas.

Some people say viruses are low priority worry, no need to spend the extra money for a device that will block viruses. The MSR Guardian is supposed to filter out viruses, and debris, and was voted top pick for international travel by one review site. Linked below.

I don’t know if your daughters’ illness would make her more susceptible to viruses or not. The Sawyer maybe all you need - low price simple, not much to break. But if you want to go the extra mile or two, consider the other options. Much of what I read about water safety comes from reading long distance hiker sites, for them low weight is king, Never carry something that weights 3 oz if you can carry something that only weights 2 oz. If super low weight is not a requirement you have more options on what to choose.

All that being said, I think that need for a water filter is over hyped to sell products. I rarely worry about it, and not when hiking areas I know well and what is likely upstream or possibly in the spring water. I’ve never gotten sick. However, if I drink something that makes me sick during a day hike from home, the worst that happens is I get really sick for a day or two, spend a lot of time sitting on the porcelain throne holding a bucket and power spraying liquid into both, in sync or alternating patterns, ewww. The risk would be higher if on a multi-day hike or otherwise in a remote unfamiliar areas, where you need to stay with a group. Water purification filtering likely a good investment , even if the expense could have been avoided. I lock my doors at night, but no one has ever come into my house when I forgot to lock them, but its’ nice to have a lock on the door.

Good luck with your choice.

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I likewise have a Sawyer and if looked after will last for years. However you need to follow the instructions to clean them carefully if they are used heavily to filter large volumes or silty water. They are also standard issue to UK special forces, which says a lot. However they tend not to have immune issues.

perhaps it would help to have the opinion of a doctor. And the advice on what is needed. For example, what exactly is it that your daughter needs to be careful of in the water? For example if it’s just bacteria and viruses then a filtration system is great, with a UV pen to be super sure. But be aware that those filtration systems do not claim to filter out chemical tainting of water sources. Frankly I have no idea how one deals with that other than iodine tablets!

If you draw a blank at your end, please let me know and I’ll ask my medical friends.

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Haha, as Mike wrote. And I’ve read similar things other places. Saying it’s more important to carry soap, or hand sanitizer than water filters.

However, this also points out the need to use a proper procedure when using a water filter. Incorrect procedure can allow contaminated water to drip or run into the filtered water, thereby recontaminating it. As much as it hurts, read the directions, do what they say. And filtering your water with dirty hands is as bad as eating a sandwich with dirty hands, after you picked it back up off the floor. :worried:

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Thank you to you all for your comments. Very helpful.
Thank you too Michael @troutrageous1 and David @dwalker for the interesting links. There is a lot to consider here and as you say some medical advice will be useful. Fortunately in the UK there is an excellent support system for Ulcerative Colitis and Crohn’s disease sufferers so I think it will make sense for my Granddaughter contact them for advice too.
In the meantime bearing in mind what you have all said I will make further enquiries.


lifestraw is an excellent product that I use all the time on the stream

The unexpected thing is it appears filtering water may be a more prudent extra cautionary step to do in towns with poor sanitation, near people. Than out in the wilderness with the animals. And I guess anytime going to a new country with different organisms in the water. That of themselves are not harmful. They’re just different from the ones at home your system is already adapted to.

Sadly true, but remember that near towns the chance of chemical tainting increases (which I understand the micro filtration systems were not designed to deal with). Not sure what one does about chemically tainted water other than avoid. I can make enquiries of you’d like.

That said, I suppose near towns there is a better chance of being able to buy bottled water. I remember being pretty far off the beaten track in India and China and finding Coke Cola branded water there. But them I guess one needs to be sure it’s genuine.

By far and away, the two most common water contaminants in US mountain streams are E. coli (coliform bacteria) and giardia (parasite). Most water filtration systems will handle these well.

Outside of the US you have to be more concerned about other bacterial species such as salmonella, shigella, campylobacter, Vibrio cholera, etc, and other parasites like Cryptosporidium. Also, viruses come into play such as Norovirus, Rotovirus and Hepatitis A.

If she is going to use the filter outside of the US, then get one that can reliably handle all of these.

Also, with UC she needs to make absolutely sure she takes her medications and not to skip days. If she is on a biologic (Remicaide or Humira, etc) or an immunomodulator (Imuran, 6MP, etc) she needs to be aware that she is slightly immune compromised and should adjust her exposure activity accordingly. Make sure she is up to date on her immunizations, but if she is on a biologic or immunomodulator she should not get live virus vaccines, such as MMR or Zoster.

She may also want to take a daily probiotic.

Just some thoughts…

-Tom (I’m a gastroenterologist)


The same problem has come up in Japan

Hokaido is wary of drinking without treating the mountain water due to parasite contamination (Echinococcus)

Contamination of coliform bacteria has occurred in many parts of Japan

In recent years, even in the spring water that looks clean has it is as it is prohibited

Fun in my mountain was to drink a “cold mountain water”
But recently I enjoy it with hot coffee

It may be because I got old :disappointed_relieved:

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Thank you Tom @tvdavisid I was hoping that you would comment as I am aware of your medical position and speciality. Your input is very much appreciated and a great help. I will pass on your comments to my Granddaughter . I don’t know what her current medication is, other than her condition appears to have stabilised in recent months. She is very sensible and is careful so I am sure she will be grateful for your advice. I think her past experience of ‘picking up’ the E.coli bug has made her realise that she must be exceedingly careful with her water source.

I am aware that she plans in the future to also visit Countries other than the USA, so she must have a system capable of filtering viruses, as well as bacteria, protozoa, like giardia & cryptosporidium. The one good point of her trips is that she always goes with recognised young persons specialist travel companies.

Thank you.


Man, you sure don’t want to get Echinococcus! Most of the patients I treated who had that were from Central America (they get it from sheep). It’s very problematic to treat.

When it comes to water it’s true that “what you don’t know can kill you!”


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Interesting that Hokkaido has an elevated concern about Echinococcus. Indicating the cautious thing to do is become aware of all the specific threats in the environments of locations you plan to visit. I recall Chris Webster posting he has Alpha-gal allergy from a tick bite in the thread about tick borne diseases. An allergy I had never heard of before.

The very best water purifier is the MSR Guardian Purifier. Yes, it’s pretty expensive, but it’s absolutely the very best product on the market. Africa, Asia, wherever, zero worries.
Filters to .02 microns!!!

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