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Light and Easy Water Filtration for the Lazy Backpacker
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Tommy Clapp

Locale: GSM Area
Nice setup, but I have a question on 11/21/2007 14:02:21 MST Print View

This is pretty cool. I think I may give it a try.

What holds the filter in place? I read the directions but when you put the filter in does it use friction to stay or do you put it in then screw the top on? Sorry for the noob question


Joseph Jacaruso
(CaptainJac) - MLife

Locale: Southeast
What Holds the Filter in Place? on 11/21/2007 14:16:42 MST Print View


The inside of the neck of the Nalgene bottle is the perfect size to hold the filter in place. Cut the hole in the cap so it is tight when you press the filter into it. That will prevent leaks. The filter slips in after the bag is fully assembled. Once you put it together the filter will pop in and out for easy replacement.

I've been using the one I made back in the spring and it hasn't missed a lick. I have started carrying an extra plastic baggie to dip water out of streams to make sure there is no cross contamination. On the AT the set up works great at any of the springs with water pipes extended out. I'm finding that the filter does not get as dirty since dirt is not forced into it by the pump.

If you have any more questions PM me and I'll post them here.

Edited by CaptainJac on 11/21/2007 14:29:37 MST.

Lance Marshall
(Lancem) - F - MLife

Locale: Oregon
DIY inline gravity filter on 11/21/2007 15:52:01 MST Print View

Here are a few pictures of another DIY gravity filter bag.

Silnylon water bag

Inside of ATB 'spigot'

Outside of ATB 'spigot'

Attach tubing to the spigot and then to an in-line filter. You can put some prefilter material inside the cap as well.
This can be made lighter by using a Platypus top instead of the Nalgene ATB top and by using less silnylon (this one hold 2-1/2 gallons).

Edited by Lancem on 03/12/2011 22:47:20 MST.

Chris Chastain
(Thangfish) - F

Locale: S. Central NC, USA
Cheap, Light (3.6oz) and Easy Gravity Water Filtration for the Lazy Backpacker on 04/18/2008 17:37:36 MDT Print View

I think I have about $30 in this thing.
Just used off the shelf stuff.

Thangfish's gravity filter

AntiGravity Gear silnylon 1 gal water bag. Appears to be just like my Brawny water bag.
Aquamira Frontier Pro disposable water filter. BPL has 'em.

Frontier  Pro filter

Marked the bottom of bag and melted a hole about the size of a dime I guess, with a red-hot pocket screwdriver.
Unscrewed the part that holds the pre-filter on the Frontier Pro and screwed it down tight on the bag. Put a 3/4" piece of hose on the filter's nipple (inside the bag) to create a silt settling reservoir. This leaves about an inch or so of water in the bag. Used the small straw/hose piece that came with the filter because it has to fit inside the nipple on the filter, and the 1/4" hose I had was a little small to fit well. Put a cut-down 1/4" hose coupler nipple on the end so I could plug it into my Platypus drinking hose.
Filled up my 2l platy while still in the pack, fairly quickly.
Filling Platypus bag in pack

The manufacturer says the filter is only good for 50 gals, but it worked well and it had already been on one weekend trip.

This is a shot of bundle size and weight. Note: this is still wet.
wet weight of filter

Edited by Thangfish on 04/19/2008 10:34:51 MDT.

Chris Chastain
(Thangfish) - F

Locale: S. Central NC, USA
Re: Cheap, Light (3.6oz) and Easy Gravity Water Filtration for the Lazy Backpacker on 05/06/2008 17:09:39 MDT Print View

Got to try this filter out this weekend.
No problems.
Here it is in use at the Thomas Knob shelter water source at Mt. Rogers. Several other people are squatting and pumping, downhill just out of the shot while they watched me take this picture, and have a handful of dried fruit.

Thomas Knob shelter water source

Here I have filled my 2 reservoirs, while my friend watches his get partially filled with the leftovers.

Thangfish's gravity filter in use

Can't wait for the Platypus gravity filter, inline replacement cartridge to arrive. Should have a much longer life span and much higher flow rate for about the same weight!

Edited by Thangfish on 05/06/2008 17:11:28 MDT.

Kyle Purcell
(dufus934) - F

Locale: North Texas
Re: Light and Easy Water Filtration for the Lazy Backpacker on 05/06/2008 18:35:45 MDT Print View

This is awesome! How did I miss this? I've got to make one of these, thanks for the post!

Glenn Tober
(glennt) - F
Light and Easy Water Filtration DIY project on 05/30/2010 09:43:19 MDT Print View

All of the posts on this subject have been very inspiring. Let me add one improvement. I recreated the equivalent of this project using only the filter, the Walmart bag set and a few dollars in extra home supply parts. In doing so, I eliminated the need to make any modifications to the filter cartridge, so if you take this approach, you don't have to grind off any threads since this method uses the Katadyne filter without modification.

I discovered that pieces from a common schedule 40 2" PVC pipe and slip end cap, sliced into a ring set, are ideally sized to replace the Nalgene water bottle parts. In practice, you push the end cap onto the pipe and then slice the common area to make a ring set. I made a set approximately 1/4 inch in thickness. You then place the inner ring on a flat surface, turn the bag inside out and position it over the inner ring, and then squeeze down the outer ring to clamp the bag in between the two rings. You then carefully cut the nylon bag out to make room for the filter and press fit the filter into the inner ring opening. Walla, you're done!

Some other hints on this method. While the outer ring slips over the inner ring very snugly by itself, it will be really snug with the nylon bag material and the filter inserted. So I first rough sanded the inside and outside diameter of the pipe to help this fit a little. If you can, plan on never taking the rings apart after you cut the bag material. It becomes difficult to line up the material the same way once they are separated. Also I used a miter saw to make rings with uniform, clean edges, although I don't see why it wouldn't work if you hand sawed the rings. To keep it safe, make sure you are cutting through both the end cap and the pipe on each cut and have enough length of end pipe to steady the assembly while cutting.

Once the bag is clamped, its a snug fit to insert the filter, which is actually a good thing. If you remove the O ring, you should be able to insert the filter all the way up to the threads and make a very tight seal that won't easily come loose. Finally, I loosely placed the filter in the hole, and then rested the assembly in the open jaws of a bench vise so that I could 'knock' the filter down using a wooden block and some gentle taps.

The whole assembly weighs 7 oz dry (9 oz damp) and filters 2 liters in 7 minutes. Here are some photos of the finished assembly. Note I slipped the O ring back on after assembly just for the sake of storing it on the filter in case I ever need the original back.Inside Out ViewOutside View

Edited by glennt on 05/30/2010 09:48:45 MDT.

Jay Wilkerson
(Creachen) - MLife

Locale: East Bay
Light and Easy Water Filtration for a Super Lazy Backpacker on 05/30/2010 10:30:50 MDT Print View

This system is Easy too and much lighter!

Brass screen filter ways 0.5oz and is used before liquid Aquamira.


Edited by Creachen on 05/30/2010 10:33:11 MDT.

Michael Davis
(mad777) - F

Locale: South Florida
Re: Light and Easy Water Filtration for the Lazy Backpacker on 05/30/2010 17:49:02 MDT Print View

Good looking design and nice weight, too!

The only potential problem I have found with gravity filters that have the filter in the collection bag, is lack of pressure for some filter cartridges.

The cartridges that have a slow flow rate, need the filter near the bottom of the tube to take advantage of the pressure from the long column of water.

But, then again, one of the nice things about a gravity filter is that you get to stop and smell the roses, while the filter is working :-)

tim hower
(jeepcachr) - F

Locale: Great Lakes
Re: Re: Light and Easy Water Filtration for the Lazy Backpacker on 06/03/2010 09:39:58 MDT Print View

[q] The only potential problem I have found with gravity filters that have the filter in the collection bag, is lack of pressure for some filter cartridges. [/q]

I've been using the Katadyn hiker base camp gravity filter for a few years and have never had an issue with it needing pressure.

It looks like it's time for me to lighten up though and convert it to use one of these walmart bags. I've got the walmart bag and the 2" pvc, just need an end cap and I'm good to go.

Edit: My Base camp filter came with a plug for the filter so I take the hose off and plug in when dipping it in the water to fill it. I never worry about cross contamination that way. I then take it back to camp and hook up the hose.

Edited by jeepcachr on 06/03/2010 09:42:52 MDT.

Josh Platt
(EasternBox) - F

Locale: Southeast
Re: Re: Light and Easy Water Filtration for the Lazy Backpacker on 06/03/2010 18:51:39 MDT Print View

I have made a filter just like the first one shown in this thread and I too have never had an issue with lack of pressure. The Katadyn filters work wonders for me.

Michael Davis
(mad777) - F

Locale: South Florida
Re: Light and Easy Water Filtration for the Lazy Backpacker on 06/03/2010 19:08:50 MDT Print View

I didn't mean to imply that this isn't a great setup. The Katadin and many other filters will function swell in this mode.

I was just trying to make the point that the filter should match the setup. I've used Sawyer's virus filter and it needs all the help it can get from gravity due to it's tiny pore size, which nearly filters out water molecules :-)

Keith Selbo
(herman666) - F - M

Locale: Northern Virginia
doing the whole job on 06/04/2010 11:57:08 MDT Print View

As far as I'm concerned, gravity filters are the only way to go. I've pumped and I've Steripened and I've waited 4 hours for chemicals to kill giardia. Nothing beats hanging a bag, finding some other task to do and coming back to purified water.

That said, I don't believe in doing half a job. Just filtering will leave viruses in the water. Chlorine will kill the viruses almost instantly, but it leaves a bad taste. What to do? I follow my Sawyer bacterial filter with a Katadyn charcoal filter. The activated charcoal removes the chlorine I added to kill viruses leaving great tasting purified water. The filter setup is pictured below. One end screws onto a platypus bag holding the dirty water. The other snaps into my Nalgene hydration bladder. The right angle under the charcoal filter is a valve. Total weight including platypus bag is 9.2 oz.
sawyer and katadyn combination

Edited by herman666 on 06/04/2010 12:18:02 MDT.

S Long

Locale: Wasatch
My own take on the water bag on 06/09/2010 22:41:03 MDT Print View

This thread inspired me to try my hand at making something like this. I used silnylon cut into a 32" diameter circle. I used the cap off a 16 ounce cheapo water bottle and a 1/4"X1/8" nylon hose fitting. I used silicone to seal the inside. It's not done yet but I plan to finish it tomorrow. Would have preferred cuben but I figured I would use what I had on hand for now. I plan to use an inline filter with 1/4" hose barbs with this water bag.water bag 1water bag 2water bag 3

tim hower
(jeepcachr) - F

Locale: Great Lakes
already had the peices on 06/10/2010 07:43:57 MDT Print View

I already had a katadyn base camp, a old nalgene, and the walmart water proof bag. I converted to the walmart bag and saved 4 onces plus it packs smaller. I only gave up a small amount of water capacity by going to the smaller bag but its still larger than what I will typically need. I thought about using the medium or small bag walmart bag but it wasn't worth the fraction of an once to go smaller.

I am not a gram weenie. I consider myself a lightweight guy not an ultralight. I'm very happy with this mod.

obx hiker
(obxcola) - MLife

Locale: Outer Banks of North Carolina
"Light and Easy Water Filtration for the Lazy Backpacker" on 06/10/2010 11:35:43 MDT Print View

If this basic set-up has been posted before my apologies.

Thanks and all credit to hammock forums Angry Sparrow: a truly creative outdoorsman.

The filter shown weighs 5 oz with the zing-it hanger( filter/bag/fittings/hanger only.... no tubing, no 2 liter platypus........ plus a wet filter weighs more for quite some time ) and can be used as a hydration system with no extra bag(drink through the filter) It could probably likely be cut to 4oz by trimming the non-filtration parts off the micro-filter and using one of Lawson/mountainfitter cuben dry bags.

The bag shown is a 4 liter Sea to Summit from REI

amgp 1s

amgp 2s

amgp s3

amgp s4

amgp s5



Apologies for the sideways shots. Fill it, hang it and forget it.

PPS: Tony; the link above has the fittings source and part #'s and them appear to be those. haha

Joe: nice job on trimming the filter! using your weight for a trimmed filter yeilds a weight for this set-up of 3.4 oz. The dry bag closure has a rigid strip around the bag rim @ 1" wide and buckles which undoubtedly "wastes" at least the .4 and likely more.

I've been encouraging Lawson at Mountainfitter to design a cuben bag for just this purpose. Come-on Lawson! A 200 gallon 3 oz smooth flowing.... not so inclined to plug-up ( hint hint frontier-pro), micro-filter gravity system/ hydration system.

Edited by obxcola on 06/10/2010 12:02:57 MDT.

Kevin Beeden
(captain_paranoia) - F

Locale: UK
drinksafe systems on 06/10/2010 12:38:17 MDT Print View

Lightweight filters do seem to have come a long way. I use one from DrinkSafe Systems.

They have ready-made gravity bag systems, too.

I know; this sounds like a commercial plug, but I have no connection with them other than as a customer.

ps. I know it's not MYOG, but it's a bit hard to MYOG viral filters...

Edited by captain_paranoia on 06/10/2010 12:39:22 MDT.

Mary D
(hikinggranny) - MLife
Light and Easy Water Filtration for the Lazy Backpacker on 06/10/2010 16:17:46 MDT Print View

Thanks, Cola, for the great pictures and the link to hammockforums for the supplies! I need to order tubing and will be making my own as soon as it arrives!

obx hiker
(obxcola) - MLife

Locale: Outer Banks of North Carolina
Light and Easy Water Filtration for the Lazy Backpacker" on 06/11/2010 19:40:44 MDT Print View

You're welcome Mary! I'd suggest you order about 3 or 4 of each part since the shipping ends up being one of the biggest expenses.

BTW The plastic end caps for closet maid shelving work great as a plug for the outlet fitting. Allows you to fill the bag, carry it around etc without the hose attached
(and held up high to keep it from draining!)

Ordered a Cuben Fiber CTF3 Rolltop Drybags @ $15.95
size: 8"x12 from mountainfitter.Quoted as 4 liters. Wish I had a bandsaw like Joe. Guess I'll carefully try the table saw. 3oz or bust!

tim hower
(jeepcachr) - F

Locale: Great Lakes
table saw on 06/11/2010 22:26:34 MDT Print View

the table saw doesn't seem like a good idea. it would only take a minute to do with a hand saw or hack saw.