LifeStraw Flex with gravity bag

Compact, lightweight water filtration system with expanded protection and 1 gallon gravity bag


LifeStraw Flex with gravity bag

LifeStraw Flex with gravity bag is rated 4.7 out of 5 by 122.


Compact, lightweight water filtration system with expanded protection and 1 gallon gravity bag

    • Next level protection against heavy metals including lead as well as bacteria, parasites, microplastics, and organic chemical matter like pesticides, and herbicides
    • Versatile water filter can also be used in 4 ways
    • Ultralight with high throughput, weighs only 6.94 oz (0.43 lbs), and capable of filtering 1 liter every 2 mins
    • This product gives back: one product, one school child, one year of clean water

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Next Level Protection

The LifeStraw Flexs cutting-edge filter can handle a wide array of contaminants found in water across the globe.

Let Gravity Do the Work

The included gravity bag takes the work out of water filtration.

Perfect Addition to Your Survival Kit

There are no batteries to replace, no moving parts to wear out, and LifeStraw products do not expire.

  • How it Works
  • Specs
  • Data & Evidence

How it Works

How It Works

Maximize protection and water throughput with this ultralight, compact gravity filtration system. LifeStraw Flex is built to provide safe drinking water in almost any environment. The 2-stage filter offers next level protection against bacteria, parasites, and microplastics while also expanding protection against lead and some chemicals. It can be used with the included gravity bag, as a straw, attached to a hydration pack, or with a plastic water bottle.

Stage 1: The membrane microfilter removes:

• 99.999999% of bacteria (E. coli)

• 99.999% of parasites (Giardia, Cryptosporidium, etc.)

• 99.999% of microplastics

Stage 2: The activated carbon + ion exchange filter reduces:

• Lead and other heavy metals

• Chlorine

• Bad odor and taste

• Organic chemical matter





  • Kit Includes: LifeStraw Flex filter, 1 gallon gravity bag, hose, backwashing syringe for cleaning
  • Filtration technology: membrane microfilter (0.2 microns) paired with an activated carbon + ion exchange filter
  • Membrane microfilter capacity: 500 gallons (2,000 liters). Pores clog over time as the filter is used; reaching end of life when water cannot pass through
  • Activated carbon +ion exchange filter capacity: 25 gallons (100 liters). With frequent use, recommended to change filter every 3 months
  • Filter Size: 6.24 x 1.5 in
  • Gravity Bag Volume: 1 gallon / 3.7 liters
  • Hose length: 27.56 in
  • Gravity bag material: TPU laminated with 210 denier nylon fabric
  • Total product Weight: 6.94 oz (0.43 lbs)
  • BPA free
  • Recyclable
  • Replaceable carbon filter available


Lab Information

We believe that responsible manufacturing includes creating and maintaining a strong evidence base for our product claims and their intended impacts. All products undergo rigorous independent testing to meet or exceed protocols established by the US Environmental Protection Agency (EPA) and National Sanitation Foundation (NSF) We also built and run an ISO accredited water laboratory based in Vietnam that does quality validation and testing of all of our new and existing products.

  • Membrane microfilter: 0.2 micron pore size. Removes 99.999999% of bacteria, 99.999% of parasites, and 99.999% of microplastics
  • Also removes silt, sand, and cloudiness
  • Activated carbon + ion exchange filter: Improves taste while reducing lead and other heavy metals, chlorine, and organic chemical matter such as pesticides, herbicides, and VOCs
  • Meets US EPA drinking water standards for bacteria and protozoa reduction
  • Meets NSF/ANSI Standard 42 for chlorine reduction, bad taste, odor
  • Meets NSF/ANSI Standard 53 for lead reduction
  • Membrane microfilter lifetime: 500 gallons (2,000 liters)
  • Activated carbon + ion exchange lifetime: 25 gallons (100 liters)
  • Filtration powered by: suction (as a straw or in-line), gravity (when paired with a gravity bag) and pressure (when used with a plastic bottle).
  • Flow rate: 0.5 liters/min
  • EPA Est. No. 95395-KOR-1
  • WARNING: Cancer and reproductive harm. Learn more


Rated 5 out of 5 by from Life Saver I really wanted to test this product out in the woods. A weekend trip into the wild gave the me the opportunity to try the LifeStraw in all modes. As a purifying straw it fit on several different water bottle brands. As gravity Bag, it held water with no leaks and provided a steady flow of water. And in a moment of bravery, because you have to a good reviewer, I tried water from a clean flowing source. Seeing as how I yet to have been crippled by parasites and bacteria I have to give the LifeStraw a 5+ star rating. My brother who is an advid outdoorsman has been eyeballing the blue beauty since I opened the box. Maybe I'll let him use it on his next hunting trip.
Date published: 2018-11-09
Rated 5 out of 5 by from Good to have for a go bag I received this free as a sample. I know that lifestraw is a good brand for water filtration of any sort of water. This item here with the bag to help filter more water and to make it easier to fill bottles is a good idea. I find that the bag it self needs a seperate clamp form the one that u fold down and clamp as the bag does open a bit. There are also no extra filters with this and i think that there should be at least 1 extra filter as 1 of the filters only lasts for 25 gallons. The instructions could be a bit more simple. As to whether this filters water i find that it does as it says it does.
Date published: 2018-10-23
Rated 2 out of 5 by from Awesome, but bag is defective I bought this, as a replacement for an old MSR gravity filter that had just had seen better days. The filter works really well, and the whole system worked better than I expected, but the gravity bag itself has two of the same clips, so that it doesn't fit together. I was really disappointed, because overall, this is a great quality water bag and filter, but I'm not able to close my bag that came with it, so I've been using my MSR bag, and some of the tubing. If it worked normally, and I could close the bag like it shows in the photos, I would give it five stars, because it is a very good quality filter
Date published: 2019-07-28
Rated 5 out of 5 by from Great for when you are on the go!! Living in Houston you have to be ready when Summer hits. The heat here is humid heat so it takes a lot out of you. I like to hike and take walks with my family. This little LifeStraw gravity bag has come in very handy on our walks. It holds a gallon of water and it has a filter so your water gets cleaned. This is truly a life saver. I highly recommend it. I would advise that you give it a good wash prior to first use. I cleaned my straw but not the bag itself the first time and the first water tasted different so make sure you clean it well. This will go a long way and its ideal for travel, hiking, walks and for the beach. I loved it!!!
Date published: 2019-08-08
Rated 5 out of 5 by from A load of my mind and back. I see the LifeStraw Flex with gravity bag as a valuable tool to have during emergency situations, travel or camping. It's such a small and lightweight design that easily packs away. Knowing you have up to 500 gallons of clean water (If you bring extra carbon filters) in your bag is a load off your mind and back. The 1-gallon bag is waterproof with a roll-top clip closure, strap to suspend the bag in the air. The bags nozzle locks in the tube to connect to the straw. It seems sturdy and protected and I see no reason it wouldn't double as a great dry bag.
Date published: 2018-10-28
Rated 5 out of 5 by from Strong, Durable Water Filter Bag I was able to use this bag for a hiking/camping trip over a 2-day/night time period and it definitely came in handy. We usually just pack a few gallons of water to bring with us, but as you can imagine, that can be very heavy with hiking. So, we decided to only pack one gallon of water, just in case, along with with water filter bag. It is very easy to fill and is lightweight when carrying. It has a little ring on top so you can hang it on a tree branch which is very convenient. It has a decent flow rate of filtering the water, and I was able to get a couple of quarts of water filtered in less in 10 minutes. I will definitely be using this more often on future hiking and camping trips!
Date published: 2019-08-08
Rated 5 out of 5 by from Perfect for hiking, camping, or emergencies!! I love this LifeStraw water filter! Extremely easy to use, fill up the bag with water from anywhere and hang it up. Just let it gravity feed through the filter and into a container. It only takes about a minute to fill up a water bottle and comes out looking clean, tasting good, and most importantly safe to drink! It’s very small and lightweight so it’s easy to pack and take with you anywhere you go. The filter itself doubles as a straw, it can even screw on to most water bottles. The straw function does work but it is a little hard to draw the water through. Overall I think this is an awesome thing to have around as a survivalist, hiker, or just in case!
Date published: 2019-08-08
Rated 5 out of 5 by from Great Features The lifeStraw is amazing, I never even knew there was products out there like this, I'm really impressed with this lifeStraw water bag, I like that its microbiological filtered, it filters and removes all kinds of bacteria and parasites that could be harmful to a human, it holds a gallon of water, you can basically get water from anywhere to drink because it will be filtered. Great in case of an emergency that you need water and get get from any body of water. This is a great product to take camping or hiking. Great product, recommend to anyone going out to camp or a hike. I would say the best product out there to always have in hand even in your car for emergencies.
Date published: 2019-08-08
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Hi, how long does the filter last? We are moving to Africa and want to get one for home use and I like the idea of the two way filter for regular use at home. I realise the carbon filter has to be replaced every 3 months. but what about the hollow filter

Asked by: Sada
The filter in the Flex lasts for 500 gallons of water.
Answered by: lifestraw
Date published: 2020-02-27

Could I use this in my camelbak as a bladder...?  Could I just fill it with 2lt at a time (camelbak capacity)...? 

Asked by: Gigi
It does say it can be used four ways but there bladder is not made for a camelpack but you can use the filter line and simple clip it into you camalpack. Does that make sense
Answered by: Guerillajib
Date published: 2019-07-14

I too, am wondering if it can be used as a bladder for trail running/long hikes? I would much rather use this and never need to worry about my water while out on the trail. Would it work?

Asked by: stickandmoose
Yes in theory you could use this to replace a hydro pack but I would say its dependent on how you hike/what you'll be doing with it. I for example have a super durable hydro pack because I'm constantly banging it against rocks or crossing streams or whatever in it. The fabric on this hydro might rip under stress
Answered by: Tbentz
Date published: 2019-07-13

For this product LifeStraw flex gravity bag mulit-function water filter, how can you be sure it is time to replace the filter for this filter bag that carries a gallon at a time? Since it can filter 500 gallons is there a indicator of some sort?

Asked by: JudyCee
The flow will be blocked and water will just stop flowing out and you know it's time; the company mentions 500 gallons but it depends on the kind of water it is filtering, the filtration capacity can go even higher.
Answered by: Shabbir
Date published: 2019-06-12
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