Sawyer Mini Gravity Feed Help

[rickb]

Can anyone point to a link that describes a simply gravity system that:

1. Uses a Sawyer Mini
2. Uses Evernew or Platypus Water bags
3. 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]

Can anyone point to a link that describes a simply gravity system that:

1. Uses a Sawyer Mini
2. Uses Evernew or Platypus Water bags
3. 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/...lon-water-bag/

I attached a valved quick connect disconnect tube fitting socket on the bag.
http://shop.linktechcouplings.com/Pa...ocket_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...-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-i...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.
gravity.gif
Have fun.

[Wil]

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]

Excellent. Thoughts on where to get 8' of tubing that won't have a plastic taste?

[nsherry61]

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]

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.

[rickb]

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]

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]

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.

[HooKooDooKu]

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]

i don't want this so sound wrong but , WHY would you got thru all this.

[HooKooDooKu]

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.

[Odd Man Out]

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.

[Dochartaigh]

If you would rather spend $9 and be done, get this:

http://www.amazon.com/gp/product/B00...rch_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.

[rickb]

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.

[squeezebox]

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.

[Kenai]

@rickb; Check out these You Tube links.


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

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

[HooKooDooKu]

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]

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]

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.

Attachment 31910

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


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