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rickb
07-23-2015, 11:21
Can anyone point to a link that describes a simply gravity system that:



Uses a Sawyer Mini
Uses Evernew or Platypus Water bags
For camp uses only


I recall that the rules of fluid dynamics required longer tubes than I might come up with myself, and something about a tornado tube attachment.

I want want to keep this simple, and not spend big bucks on for a hydration system reservoir. Doing this in a McGiver-like would be great, because that will impress my wife.

Odd Man Out
07-23-2015, 12:47
Can anyone point to a link that describes a simply gravity system that:



Uses a Sawyer Mini
Uses Evernew or Platypus Water bags
For camp uses only


I recall that the rules of fluid dynamics required longer tubes than I might come up with myself, and something about a tornado tube attachment.

I want want to keep this simple, and not spend big bucks on for a hydration system reservoir. Doing this in a McGiver-like would be great, because that will impress my wife.

How timely. I am currently working on a system like this and just got phase one done last night. But that also means I don't have any field test data yet. What I did was get an AGG 1 gallon water bag:
http://www.antigravitygear.com/shop/hydration/antigravitygear-1-gallon-water-bag/

I attached a valved quick connect disconnect tube fitting socket on the bag.
http://shop.linktechcouplings.com/Panel-Mount-Hose-Barb-Socket_c106.htm

The matching quick disconnect plug with a hose barb goes on the tube ("straw") that comes with the Sawyer Mini
http://shop.linktechcouplings.com/In-Line-Hose-Barb-Plug_c188.htm

The straw attaches to the inlet nipple on the filter. Hang the bag and the water flows out the other end. For collecting water you have four options.

1. Let the water drip from the filter into a bottle underneath
2. Attach a tube on the outlet nipple of the filter and let that drain into a bottle.
3. Attach the outlet tube to a bladder using a tube-to-male thread adapter.
4. Attach a bladder (with compatible threads) directly to the filter.

I was experimenting with the AGG water bag and quick disconnect fittings to see if that might be a light weight and convenient way to collect and filter water. The plan is to attach a string to the bag so I can drop it in the steam/pond to fill. Then carry it back to camp, plug in the filter, and start filtering. I can also let the bag hang for a while to sediment settle if desired. I could also attach a particle pre-filter to the inlet barb inside the bag. Since I haven't field-tested yet, I can not yet say how that will work. Attaching the fittings to the bag was a bit of a pain and my first attempt had a very slow leak (not enough to make it unusable, but enough to be annoying). Also if that connection is not durable in the field, then this system may need some more work. Because you want to keep this cheap and simple, you may want to try another quick, easy, and less expensive way of attaching a dirty water reservoir:

1. You could screw a dirty water bladder (with compatible threads) directly to the inlet side of the filter. I know the Evernew threads match perfectly. I have read that the Platypus thread do not, but some people say it will work. Smart Water bottles definitely fit too.

2. You could also use the Sawyer adapter kit (the blue fitting) to connect the bladder to the filter the tube. The Tornado Tube is an adapter that has female threads on both sides. I believe this was more useful with the original Sawyer Squeeze which is threaded on the outlet side. The mini is not (and has no male threads) so I think the Sawyer tubing adapters would be easier.
https://sawyer.com/products/sawyer-inline-hydration-pack-adapters/

3. You could even use a 2 L pop bottle or a Smart Water bottle (any bottle with compatible threads) with a hole in the bottom as a reservoir. But what ever you use the dirty water reservoir has to be either collapsible (like the bladder) or with an opening on top to let air in.

Whatever your use, you will probably want to rig up some way of hanging this from a tree branch. The AGG Water Bag comes with a handle. My plan is to attach a piece of string so I can just dip it in a lake/stream to fill (no more we feet when filling bottles?). If using a bladder or pop bottle, you would have to rig up something with rope/string to hang it when filtering.

On the outlet side, you also have to make sure you use either a flexible bladder or an open container. An advantage of using a bladder on the outlet side is you can attach it and let it go and do some other camp chores. When the bladder is full, the flow will stop until you come back and disconnect. For this to work you need to squeeze all the air out of the receiving bladder so air pressure doesn't stop the flow before the bag is full of water.

The flow rate will be determined primarily by two factors. One is the resistance to flow in the system, which could be limited if your filter becomes clogged or if your tubing is too small. The other is the pressure that is pushing the water through the system. This is proportional to the vertical distance between the top and bottom of the water column. Note that it doesn't matter how much water you have. It is only the vertical distance that matters. Also, it shouldn't matter if the filter is at the top, middle, or bottom of the system, as long as the inlet and outlet tubes are filled to the top and bottom.

In my first trial last night, it took 2 min and 50 sec to fill a 16 oz pop bottle (1' 25" per cup). Unfortunately I didn't measure the height of the water column, but I would guess that the bag, tube and filter was about two feet tall when hanging from my kitchen cupboards and dripping into my pop bottle. I measured the flow rate when the bag was full and also when it was nearly empty. Because the water level drops as the bag empties, you would expect the flow rate to decline as well. However I found that the flow rate was fairly constant until the bag was almost empty. When I get home tonight I can measure that distance for you. If that flow rate is adequate for your needs, then you could get by with that type of system. If you feel you a higher flow rate, you could get more tubing to get a higher water pressure.
31430
Have fun.

Wil
07-23-2015, 12:50
Doing this in a McGiver-like would be great, because that will impress my wife.Stick with Evernew bags because the threads are standard. Get the tubing at Home Depot. Four feet minimum; eight is better. Drill holes in two soda bottle caps same size as tubing, force the tubing through the holes. Paper bunch two holes in the bottom corners of one Evernew bag and string some cord through for hanging.

Do a search and there are several descriptions of more elegant systems: using bottle caps with the tubing connections built-in; flexible tubing that is easier to handle (also some people say they pick up a plastic taste from the simple tubing); a tubing clamp for turning on and off.

rickb
07-23-2015, 13:24
Excellent. Thoughts on where to get 8' of tubing that won't have a plastic taste?

nsherry61
07-23-2015, 14:18
Most common bulk vinyl tubing that you would buy in a home improvement/hardware store is NOT safe, food-grade tubing. However if you find some that is, that would be the least expensive source. Both Camelbak and Platapus sell replacement tubes that work well and can be found out your local outfitter. They're not 8' long, but they don't need to be. They are four to six feet long and either way, that should be enough hydrostatic head to get a good flow going.

HooKooDooKu
07-23-2015, 14:51
Here's (a fuzzy picture) of my test setup in the kitchen.
http://whiteblaze.net/forum/vbg/files/1/1/8/7/1/sawyer.jpg
It's simply an Evernew 2L bladder directly attached to the Sawyer Mini, and a Platypus Hoser (bite valve removed) with hose pushed onto the nipple of the Sawyer.

Dochartaigh
07-23-2015, 14:59
If you would rather spend $9 and be done, get this:

http://www.amazon.com/gp/product/B00EURFBKI?psc=1&redirect=true&ref_=oh_aui_search_detailpage

You want to use the largest part that's shown in the picture which has the white connector part, going to the gray tube, going to the blue colored water bottle cap.

Remove the white part, stick that gray tube on the end of your Sawyer mini (on the clean water side on the Sawyer) and you're done. Either I haven't gotten my Sawyer mini dirty enough, but I haven't needed to have several feet of tubing to get it to gravity fill yet (it does shorten the time when I use the tubing though - but I wanted as small and lightweight a setup as possible).

Mine goes: Evernew dirty water bladder on top, upside down (with some string to hang it from a tree/branch) > Sawyer filter > $9 adapter part > clean Evernew water bladder.

squeezebox
07-23-2015, 15:32
Bolt 2 soda bottle caps together, rust proof bolt, silicone in-between caps. Drill some holes through the 2 caps for water flow. This connects Sawyer output with platypus input. The 1/2 gal bag that comes with the Sawyer filter screws to the filter input. Voila! gravity feed without tubing.

rickb
07-23-2015, 15:46
Here's (a fuzzy picture) of my test setup in the kitchen.

It's simply an Evernew 2L bladder directly attached to the Sawyer Mini, and a Platypus Hoser (bite valve removed) with hose pushed onto the nipple of the Sawyer.

Did you make the hole in Evenew (to hang the bag) with a common paper punch?

If so, was that a good move (ie do you think it will be strong enough without a grommet)?

rickb
07-23-2015, 20:09
OK, that was fun.

Done. Almost perfect. Definitely a "why didn't I listen to you guys a year ago" project.

The paper punch worked great on the Evernew bags.

I ended getting the Sawyer adapter at REI. The bottle cap suggestion wouldn't work on the Mini (not mine, anyway) because the output side of the Mini does not have any threads.

With 6 feet of hose, water flow through much faster than I would have thought. I will probably cut it down some, but for now I am declaring victory.

The "less than perfect" part is the hose itself. It was from Home Depot and made by Watts, supposedly for ice makers and such. It was labeled "no lead" on the big tag but the small print said that the lead content was .25% and then there were the California Cancer warnings.

I think I will search for anothe hose as some have suggested. Apart from those issues, the crystal clear tubing was harder than your typical surgical tubing-- so it took more effort to put over the Sawyer nipple.

Plus you never know when you will need to jerry rig a wrist rocket to get your bear bag rope up cover a difficult branch (or not, just having a McGiver Fantasy on that one).

Thanks for the help.

Edit -- The other less than perfect part is now that I have a hanging bag with a hose I need to find a shower head.

Wil
07-23-2015, 21:05
The bottle cap suggestion wouldn't work on the Mini (not mine, anyway) because the output side of the Mini does not have any threads.I guess I wasn't explicit enough.

First cap goes in the dirty water bag and its short attached tubing into the filter's input barb. Second cap goes onto the clean water bag and its long attached tubing onto the filter's output barb.

I like to use the short length from the dirty bag to the filter for flexibility, e.g. other uses for the setup, and because I think there is a slight improvement in throughput.

I once asked a plumber about the Home depot tubing. No lead means under a certain level (everywhere but in California). He says he uses it as do most of his colleagues. Not that plumbers know anything about water, just a data point. When I got mine there were two types, one a little more flexible. Amazon has thinner-walled and much more flexible tubing, as do other places. It can be expensive stuff.

rickb
07-23-2015, 22:21
Remove the white part, stick that gray tube on the end of your Sawyer mini (on the clean water side on the Sawyer) and you're done. Either I haven't gotten my Sawyer mini dirty enough, but I haven't needed to have several feet of tubing to get it to gravity fill yet (it does shorten the time when I use the tubing though - but I wanted as small and lightweight a setup as possible).

I tried just 6" the gray tube. For me that way was too slow.

HooKooDooKu
07-24-2015, 01:45
Did you make the hole in Evenew (to hang the bag) with a common paper punch?

If so, was that a good move (ie do you think it will be strong enough without a grommet)?

A standard hoke punch works just great. For one, you get a nice clean hole to reduce the chance of ripping. Second, the spot where the hole is punched goes thru two seperate layers (where the Evernew expands for the 'bottle' (bag) to stand up). So the stress is across two layers. Finally, the string is thicker that a tiny price of string (2 or 3 mm cordage). Haven't had any tearing issues.

Back on the trail
09-03-2015, 16:02
i don't want this so sound wrong but , WHY would you got thru all this.

HooKooDooKu
09-03-2015, 17:04
i don't want this so sound wrong but , WHY would you got thru all this.
'This' is an indefinite reference. I can only ASSUME you mean the whole concept of setting up a gravity feed system rather than just squeezing.

If my assumption is correct, I'll answer that with one word: 'Convenience'.

An ultra-light gram weeny will want to forgo the extra weight of hoses and such. But I've seen first hand what a burden it can be to try to squeeze water directly from the Sawyer into a water container.

To make things a little easier on me, I like being able to simply hang my dirty water bladder and letting the water filtration progress at its own rate while I take care of other tasks... by simply adding the weight of a short piece of hose (and connector) and a short piece of string to hang it by.

Kenai
09-03-2015, 18:25
@rickb; Check out these You Tube links.


https://www.youtube.com/watch?v=VUehUWAfjPk

https://www.youtube.com/watch?v=5S5UCqoiE7A

Odd Man Out
09-03-2015, 19:54
i don't want this so sound wrong but , WHY would you got thru all this.

I used my gravity system on my hike last week and it worked pretty well. Mine is admittedly a bit more complicated (probably too complicated) but as to why do this, I really appreciated being able to go down to the water source just one time to fill a 1 gallon reservoir and bring it back to camp (water sources are often quite a hike down hill from the camp sites, as was the case on my hike last week). Once back in camp, I could hook up a Evernew bladder for collecting clean water and let it go while doing camp chores. A bit later I would go back, swap the full bag for an empty, and go do more chores. I was filtering for two people so a bit later I would go back, use the full bag to refill other containers and repeat.

BTW, I did find it helpful to suck on the clean water outlet hose to suck all the air out of the filter and tubing to get the best flow. I was using a very short tube so this may be less critical if I go out and get a longer tube.

HooKooDooKu
09-04-2015, 00:00
My tube is about 3ft long and with a new filter and clean water source, I can filter about 2 gallons in 4 minutes (with no squeezing the bag or doing anything else to prime the tubing). But it does help to get as much air as possible out of the clean water bag before starting. It seems that the act of filtering the water thru such tiny pores seems to release some of the disolved air from out of the wayer.

Odd Man Out
09-04-2015, 09:53
My tube is about 3ft long and with a new filter and clean water source, I can filter about 2 gallons in 4 minutes (with no squeezing the bag or doing anything else to prime the tubing). But it does help to get as much air as possible out of the clean water bag before starting. It seems that the act of filtering the water thru such tiny pores seems to release some of the disolved air from out of the wayer.

Yes that makes sense. There will be a sudden pressure drop as the water goes through the filter pores. This is the pressure that forces the water through the filter. That drop in pressure will tend to cause dissolved air to be released as a gas (like opening a pop bottle releases dissolved CO2). When I sucked on the hose to get the flow going, it felt like I was drinking a carbonated beverage through a straw. You can sort of feel the tiny bubbles form as you suck. This afternoon's committee meeting was canceled because of the holiday weekend so I will leave work early to go shopping for a longer hose.

rickb
09-07-2015, 17:45
Thanks for everyone's help.

I got a valve at the beer making store, which also serves to make a quick and easy connection to the hose at the top.

I also bought a Sawyer connect kit which for the Evernew bag. Since the Sawyer connection kit had a second male attachment, I hooked that up to my old PUR output hose for filling up a hard water bottle directly. I may ditch that as being "too much.

Takes about 7 minutes for 2 liters.

Here are are some photos.

31910

31911
The valve stays permanently connected to the filter, but the hose slides off and on the output side easy -- but stays on snug.


31912

31913

31914

krshome
09-10-2015, 20:36
Here is my Sawyer Mini gravity filter. I made special caps with quick connects that are valved https://www.freshwatersystems.com/p-7944-apc-valved-male-thread-coupling-body-14-npt.aspx31958
These replace all the caps on all my bottles. the silicone tubing is https://www.freshwatersystems.com/p-9003-silcon-silicone-tubing-316-id-x-516-od-x-1.aspx The 3/16 ID works better than the larger sizes others are using.
The system is almost a copy of the platypus system about 1 foot of tubing to the filter dirty side and about 4 feet of tubing with a hose clamp on the clean end.
31959


One last thing to add is a small attachment that is used to shower with when clicked into a water bag.
3196031961


If you go the bidet route it will click into a bottle
3196231963
The whole kit it a little heavier than just using a mini, but a total weight of 8oz to have 4+liters of water carrying capacity, shower and a filter i'm ok with that.

The clean bag can be a hydration bladder which is what I actually do. I have a 1.5 liter Evernew bag with a DIY quick connect pickup straw. https://www.freshwatersystems.com/p-3055-apc-valved-in-line-ptf-coupling-body-with-shroud-14-ptf.aspx with refrigerator ice maker water line connected to it. I locate it in a side pocket of my pack for easy access.
31964

rickb
09-16-2015, 07:11
One last thing to add is a small attachment that is used to shower with when clicked into a water bag.
3196031961




Very nice!

Two questions:

Where did you source the shower head attachment?

Any experience with plugs for the custom caps? So that you could carry dirty water to your campsite in your pack without replacing the custom cap with a regular one.

krshome
09-16-2015, 07:17
The shower head is from the old MSR shower kit no longer available but sure the new version should work. The caps have valves in them so no plugs are needed. When you click the hose on the cap water flows when unplugged water shuts off. Nice thing is no need for extra caps to loose.


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Five Tango
09-19-2015, 10:05
Sorry,but I am at a loss as to how you attached the plumbing fitting to the AGG bag?Thanks!

SWODaddy
09-19-2015, 15:57
What worked really well for me was to buy a platypus dirty water bag (you can buy just the bag). It has a zip top that makes it easy to collect water along with a nylon strap that makes it easy to hang. It uses a quick release fitting that's about a half inch from the bottom so sediment won't clog your filter as easily.

From there, I just bought some tubing and quick release fittings that allows me to refill my bladder in my pack or a bottle. I can use gravity in camp, or squeeze the dirty bag for a quick fill up. Everything packs nicely inside the dirty bag.

Five Tango
09-19-2015, 17:45
Yep,I also have the Platypus dirty bag and can use either Sawyer filter with it to fill my Hydrapak reversible clean water bag or any other bag or bottle.I would like to be able to plumb a bucket style bag or buy one already plumbed since they are so easy to fill.Gives another option.Any ideas?

Odd Man Out
10-14-2015, 11:54
I posted earlier about my gravity system with a sylnylon bag and quick disconnect fitting. I used that this summer with mixed results. The bag tended to leak and was not as easy to fill as I had hoped. I appreciated being able to get a gallon of water and carry it back to camp, especially since I was filtering for two people. But for my solo trip last weekend, I opted for a much easier system.

I have two Evernew Water Carry bladders (900 mL/30 oz each). One I use for dirty water the other for clean. I got the Sawyer adapter for connecting the a bladder to a hose (same as Rickb above). I cut a 1" piece of the grey hose/straw that came with the filter to connect the adapter to clean side of the filter. So when you piece it all together it is: dirty bladder - filter - 1" tube - adapter - clean bladder. I also punched two holes in the perimeter of the dirty bladder near the bottom (not to puncture the bladder) and tied a short loop of string through it so I can hang it from a branch for gravity filtering. This also helps me keep track of which bladder is which (string=dirty / no string=clean). Using a bladder for clean water allows for a convenient gravity system and provides a backup in case the dirty bladder breaks. I also I also carry a very thin water bottle with the top cut off as a scoop to fill the bladder. I also carry two 20 oz Gatorade bottles for drinking from while hiking (they attach to the pack straps). This gives me 100 oz of total capacity if I hit a dry stretch of trail.

Last Saturday, I was going to camp on a bluff with no water source, so I filled my dirty bladder at a stream crossing using the scoop. Then when I got to camp, I take out the filter, attach the clean bladder (rolled up so there is no air in it), attach the dirty bladder full of water, hang from a branch by the string, and go set up camp. By the time camp chores were done, all the water had flowed into the clean bladder - enough for dinner, evening tea, and morning coffee. A longer hose gives faster filtering, but for this application, speed was not an issue for me as it filters while I'm doing camp chores. It is a closed system so there is no need to monitor. When I stopped during the day to refill my Gatorade bottles, I just used it in squeeze mode and it only took a minute to fill the bottles.

I can also use the same set up for back flushing. Just disconnect the dirty bladder and squeeze the clean bladder to force water backwards through the filter (I have not used the syringe). I will make sure the clean bladder is just partly filled when back flushing. When all the water is through, I keep squeezing to see if air will go through the filter. You should find that even with extra pressure, air will not go through the filter. I have used 0.2 micron filters in the lab for filter sterilization. I know from this experience that you easily force liquids through a wet filter but not air. We would use this test to make sure the filter was intact and the sterilization was successful. The Sawyer filter (also 0.2 micron) seems to behave the same way. I can not guarantee that this test is 100% reliable for an intact filter, but if I could force air through it when wet, I would definitely replace the filter. BTW, if you are not getting good flow through your filter, make sure you don't have air bubbles in the system.

There are some on-line reviews of Sawyer filter becoming clogged or having poor flow rates. I suspect this may be due to hard water scale building up when the filter dries out. I'm not sure this is the case, but it would make sense based on the way a Sawyer filter works. Since I am using my filter every day it shouldn't dry out while hiking. At home I prevent this possibility by back flushing with distilled water as soon as I get home. After several trips, my filter seems to still be flowing like new. Some people report they don't like the Sawyer Mini because it is too slow. I wonder if their filter isn't working correctly due to air bubbles or scale buildup, since with this care, mine flows plenty fast (at least for my needs).

Drum Man
03-05-2017, 11:05
Here is my Sawyer Mini gravity filter. I made special caps with quick connects that are valved https://www.freshwatersystems.com/p-7944-apc-valved-male-thread-coupling-body-14-npt.aspx31958
These replace all the caps on all my bottles. the silicone tubing is https://www.freshwatersystems.com/p-9003-silcon-silicone-tubing-316-id-x-516-od-x-1.aspx The 3/16 ID works better than the larger sizes others are using.
The system is almost a copy of the platypus system about 1 foot of tubing to the filter dirty side and about 4 feet of tubing with a hose clamp on the clean end.
31959


One last thing to add is a small attachment that is used to shower with when clicked into a water bag.
3196031961


If you go the bidet route it will click into a bottle
3196231963
The whole kit it a little heavier than just using a mini, but a total weight of 8oz to have 4+liters of water carrying capacity, shower and a filter i'm ok with that.

The clean bag can be a hydration bladder which is what I actually do. I have a 1.5 liter Evernew bag with a DIY quick connect pickup straw. https://www.freshwatersystems.com/p-3055-apc-valved-in-line-ptf-coupling-body-with-shroud-14-ptf.aspx with refrigerator ice maker water line connected to it. I locate it in a side pocket of my pack for easy access.
31964
Love this setup.

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krshome
03-05-2017, 11:11
Thanks DM, I have some extra caps with the quick connects you can have if we ever hang out again[emoji16]


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Drum Man
03-05-2017, 11:12
Thanks DM, I have some extra caps with the quick connects you can have if we ever hang out again[emoji16]


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Awesome! You and I should just go somewhere.

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krshome
03-05-2017, 18:14
Starting to plan trip now most local but a Mount Rogers trip is in the works too. As per my water set up I have made my favorite now and think I'm done playing around with trying to make it better. It's simple and cheap. If your interested let me know I'll go into more detail


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Drum Man
03-07-2017, 15:00
That sounds good

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Time Zone
10-08-2017, 10:38
I decided to experiment a bit here at home with a gravity feed water filtration system using my Sawyer Mini. I'm not terribly concerned with flow rate, as the plan would be to set it up and let it run while doing other camp chores. As long as it worked ... which is the catch.

I had hoped to set up a system whereby one of my 1L soda bottles would be the dirty water reservoir. I figured out a way to hang that upside down, with the mini screwed on in place of the cap, and for completeness I affixed the gray tube to the outflow side, and let it drain into another 1L soda bottle standing upright. Except - nothing.

At first, I thought, well, the mini was totally dry, it'll take some time for water to soak through the layers of filter. After 5 min, I gave the "dirty" bottle a little squeeze to help things along. As I squeezed, couple bubbles went up, a little water dripped down, and I thought I was on my way. But then, nothing more.

It occurred to me that the lack of pressure equalization in the dirty water bottle was keeping it from flowing out. It made sense to me as the only other time I used the mini (as a filtering cap to a soda bottle), the bottle collapsed as I sucked untreated water out of the bottle through the Mini, and I had to unscrew the Mini periodically to let the bottle pop back into shape and resume a good flow.

So, short of punching holes in the (top) of the dirty water bottle, it's not really going to work this way? How is this not an issue with a water reservoir/bag? Just because the sides are more flexible and more collapsible? Is it the case that the same forces are at play with the soft-sided bag, but just not as noticeable because of the greater ability to collapse? That is, theoretically: if you poked a hole in the top of a dirty water bag halfway through its emptying through filtration, the flow would likely increase due to pressure equalization? (forgive me if that's not the right physics term)

Anyway, I had hoped to have a bottle-to-bottle filtration system, but, short of finding a bottle with a cap at both ends, I don't think it's going to work, so I'll probably need to get something like an Evernew bag instead.

Thanks in advance for any thoughts on this.

Deacon
10-08-2017, 12:24
I decided to experiment a bit here at home with a gravity feed water filtration system using my Sawyer Mini. I'm not terribly concerned with flow rate, as the plan would be to set it up and let it run while doing other camp chores. As long as it worked ... which is the catch.

I had hoped to set up a system whereby one of my 1L soda bottles would be the dirty water reservoir. I figured out a way to hang that upside down, with the mini screwed on in place of the cap, and for completeness I affixed the gray tube to the outflow side, and let it drain into another 1L soda bottle standing upright. Except - nothing.

At first, I thought, well, the mini was totally dry, it'll take some time for water to soak through the layers of filter. After 5 min, I gave the "dirty" bottle a little squeeze to help things along. As I squeezed, couple bubbles went up, a little water dripped down, and I thought I was on my way. But then, nothing more.

It occurred to me that the lack of pressure equalization in the dirty water bottle was keeping it from flowing out. It made sense to me as the only other time I used the mini (as a filtering cap to a soda bottle), the bottle collapsed as I sucked untreated water out of the bottle through the Mini, and I had to unscrew the Mini periodically to let the bottle pop back into shape and resume a good flow.

So, short of punching holes in the (top) of the dirty water bottle, it's not really going to work this way? How is this not an issue with a water reservoir/bag? Just because the sides are more flexible and more collapsible? Is it the case that the same forces are at play with the soft-sided bag, but just not as noticeable because of the greater ability to collapse? That is, theoretically: if you poked a hole in the top of a dirty water bag halfway through its emptying through filtration, the flow would likely increase due to pressure equalization? (forgive me if that's not the right physics term)

Anyway, I had hoped to have a bottle-to-bottle filtration system, but, short of finding a bottle with a cap at both ends, I don't think it's going to work, so I'll probably need to get something like an Evernew bag instead.

Thanks in advance for any thoughts on this.

I just weighed the sawyer sp131 filter that came with my big zip (never used it so the filter is dry), and weighs 2.75 oz. That’s just 0.75 oz. more than a mini.

It is a little larger than the standard squeeze, but for an additional 0.75 oz, you would have a gravity system with good flow.

https://uploads.tapatalk-cdn.com/20171008/25aa891c15d22301e3c61ae002b67ab1.jpg


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HooKooDooKu
10-08-2017, 12:41
I decided to experiment a bit here at home with a gravity feed water filtration system using my Sawyer Mini. I'm not terribly concerned with flow rate, as the plan would be to set it up and let it run while doing other camp chores. As long as it worked ... which is the catch.

I had hoped to set up a system whereby one of my 1L soda bottles would be the dirty water reservoir. I figured out a way to hang that upside down, with the mini screwed on in place of the cap, and for completeness I affixed the gray tube to the outflow side, and let it drain into another 1L soda bottle standing upright. Except - nothing.

At first, I thought, well, the mini was totally dry, it'll take some time for water to soak through the layers of filter. After 5 min, I gave the "dirty" bottle a little squeeze to help things along. As I squeezed, couple bubbles went up, a little water dripped down, and I thought I was on my way. But then, nothing more.

It occurred to me that the lack of pressure equalization in the dirty water bottle was keeping it from flowing out. It made sense to me as the only other time I used the mini (as a filtering cap to a soda bottle), the bottle collapsed as I sucked untreated water out of the bottle through the Mini, and I had to unscrew the Mini periodically to let the bottle pop back into shape and resume a good flow.

So, short of punching holes in the (top) of the dirty water bottle, it's not really going to work this way? How is this not an issue with a water reservoir/bag? Just because the sides are more flexible and more collapsible? Is it the case that the same forces are at play with the soft-sided bag, but just not as noticeable because of the greater ability to collapse? That is, theoretically: if you poked a hole in the top of a dirty water bag halfway through its emptying through filtration, the flow would likely increase due to pressure equalization? (forgive me if that's not the right physics term)

Anyway, I had hoped to have a bottle-to-bottle filtration system, but, short of finding a bottle with a cap at both ends, I don't think it's going to work, so I'll probably need to get something like an Evernew bag instead.

Thanks in advance for any thoughts on this.
The bottle's resistance to collapsing creates a force in opposition to gravity... effectively air pressure is helping to hold the water in the bottle.
Use a soft sided bottle and that force is removed.
I've never had an issue using a 2L Evernew bladder screwed directly on the mini. The alone is enough to allow water to trickle out. But I also add a 3' hose to connect the Mini to a Playtypus hozer (note that I replaced the thick stiff hose that came with the Platypus hozer with the tubing from my old SweetWater filter). When fully extended such that the hose is nearly vertical and filled with water, the water pressure from the hose helps to suck the water out of the filter increasing the flow rate. A 10' column of water produces about 4psi of pressure, so my 3' hose regularly creates about 1psi of suction.
If you see my test setup from earlier in this thread, my system of a 2L Evernew screwed directly to a mini, and the hose from the Platypus pushed directly on the nozzle of the mini will filter 2L in 4 minutes with a brand new filter with no priming.

rickb
10-08-2017, 13:16
I had hoped to set up a system whereby one of my 1L soda bottles would be the dirty water reservoir. I figured out a way to hang that upside down, with the mini screwed on in place of the cap, and for completeness I affixed the gray tube to the outflow side, and let it drain into another 1L soda bottle standing upright. Except - nothing
.

In addition to using a collapsing bag, the grey tube on the outlet side is very short

If you increase the length of the tube — even though it is on the outlet side — to say about 3 feet, the pressure through the filter will increase substantially.

This makes no logical sense, I know. God bless the engineers who built our world.

murdocsboss
10-18-2017, 21:58
I use a 10 liter sea to summit pocket shower and medical grade silicone tubing. The cheapest option being replacment enema tubing. It connects by way of a 90 degree stop cock taken from an old platypus. I use a first need or a sawyer mini depending on trip length.

j_jones84
10-07-2018, 01:07
Mine is pretty simple. Used a hole punch in 2L sawyer bag and tie 10ft of string. Just above where the string attaches to the 2L I have another string with a bowline on the free end and a prussik around the 10ft string line. I drilled a tiny hole in the drinking part of a flip top smart water bottle. I attach the drilled cap to a 1L bottle and loop the bowline through the string to make a running bowline. I shove the sawyer into the drilled cap and adjust the prussik up so the weight is on the line. Took an hour to build. No parts needed other than a smart water bottle flip top and some string.

Odd Man Out
10-07-2018, 14:30
I recently picked up a Versa Flow filter from Hydroblu and although I haven't had a chance to use it in the field yet, I'm really liking the tests I have done at home. I have not seen this filter discussed much but for me it has a number of advantages over some of the better known filters, including the Sawyer Mini which is what it replaced in my kit. The Versa Flow's overall construction is similar to a Sawyer Mini or Squeeze. All have female threads on the dirty side you can attach a water bladder or bottle to the dirty side and squeeze water through. But unlike the the Sawyer filters, the Versa Flow has female threads on the clean side (vs a hose connection on the Mini and male threads on the Squeeze) so you can attach a water bladder directly to the clean side for a closed system that can filter unattended with no adapters or tubing necessary. In my experience, the tubes used in gravity systems to get a more hydrostatic pressure (and thus increase flow rates) are unnecessary. If I want to filter faster, I squeeze the dirty water bladder to increase pressure. I gravity filter when I am off doing camp chores so much about flow rates. The filtering has always been done by the time I come back. I wanted a system that doesn't need adapters and tubing as they seemed to be more trouble than they were worth.

The Versa Flow looks to be about the size of a Squeeze, but shaped like a Mini (photo below). I do believe the flow rate of the Versa Flow (like the Squeeze) is substantially faster than the Mini, although I can't do a side by side comparison as my Mini has bought the farm after several years of use. I a simple flow test of the Versa Flow, I found it took 2 min and 45 sec to fill a 700 mL Smartwater Bottle by gravity flow from a filled 900 mL Evernew bladder and 2 min 10 sec from a filled 2 L CNOC bladder. On my crappy kitchen scale, the Versa Flow weighs 70 g (wet, but drained) vs 50 g for the Mini. But without the need for adaptors and hoses, the system weight of the Versa Flow is probably about the same or less. Also, when I hung a clean water bladder to the Mini with a hose and adapter, I have occasionally had the hose pull off the filter due to the weight of the water in the clean side bladder. This can't happen when the clean water bladder is threaded directly to the filter.

With any new filter there is always the issue of thread compatibility. I have seen mixed reports online about which filters fit on which bottles. The Versa Flow is has the same standard threads as the Mini, soda and Smartwater bottles, and some bladders (Sawyer, Evernew, and CNOC). I know there are others with compatible threads, but these are the only ones I have experience with. However I did see one difference between my Versa Flow and the Mini. The Mini did not seal with my new CNOC bladder. The fact that both filters were compatible with all other threads lead me to think there was some other issue. What I concluded is that the threads on the CNOC bladder were shallower and made of a flexible plastic (vs the more rigid plastic on all the other bottles). Also the Versa Flow had deeper threads and had a different style gasket at the base of the threads with a rim to seal against the mouth of the bottle like the lids of a soda or Smartwater bottle. The Mini seems to have shallower threads and a flat rubber gasket to make the seal. The fact that the Versa Flow worked with all bottles leads me to conclude that its connections are more compatible with various bottles and bladders.

The Versa Flow also had rubber caps tethered to both sides for capping the filter on both sides which is handy. My Mini only had a cap on one side. The Versa Flow caps can be easily taken on and off in case a gram weenie does not want them. The only down side I see with my new system is that with the same threads on both sides of the filter, you have to take care not to attach your dirty side bladder to the clean side of the filter and filter backwards (thus backflushing all the gunk from yesterday into your clean water bottle). The flow direction if marked on the side of the filter and the caps are color coded (grey=dirty, blue-clean). However being able to thread a bladder on the clean side does make it easy to backflush with a bladder or soda bottle. For those who backflush by attaching the drinking spout of a 700 mL Smartwater bottle on the hose connector of your Sawyer, that also works on the Versa Flow.

http://hydroblu.com/versa-flow-light-weight-water-filter/

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