Simple valve makes Sawyer Mini filter work better with generic plastic water bottles

[Jan Miksovsky]

I’m a fan of the Sawyer Mini water filter (https://sawyer.com/products/sawyer-mini-filter), but am unsatisfied with its general reliance on collapsible bottles. I find collapsible bottles too finicky to fill up, challenging to stand upright on the ground, and cumbersome to slide into a pack’s side pocket. I’d rather use a rigid, lightweight plastic bottle.

The problem is that the design of the Sawyer Mini doesn’t allow air to get back into the bottle to replace the water being drawn out. The resulting vacuum quickly makes it hard to suck water out. You have to periodically loosen the filter to let air into the bottle to relieve the vacuum, or constantly crush and re-expand the bottle.

One simple way to fix this problem is to add a one-way “duckbill” silicone valve to a PET bottle:

Such a valve lets air in, but won’t let water out. When you drink through the filter, air bubbles indicate that air is entering the bottle to relieve the vacuum:

I haven’t yet found a cheap source of such silicone valves. Since they’re generally sold as parts for larger products, Internet sources seem to only offer them in large lots. Blue Desert will sell you a single valve as a replacement part (http://www.bluedesert-shop.com/#!product/prd1/2463039021/one-direction-valve-for-smartube%25c2%25ae-cap), although it’s ridiculously expensive: $8 for a part that probably costs a pennies. Still, a collapsible bottle can run $10–20, so the total cost here is still competitive.

Installing such a valve is trivial. First, find a PET water bottle whose threads fit the Sawyer filter. (Not all brands will work. I just bought two bottles of water, and the second one worked fine.) At the top of the bottle, drill a hole that’s just a bit wider that the valve’s narrowest part. Push the valve in the hole, and it should snap into place.

I really enjoy this water system. PET bottles are inherently light, and the valve adds negligible weight. (The Blue Desert page above states 10g, but I measure it as less than 1g.) Combined with the Sawyer Mini filter, you get a safe, low-hassle drinking system. And if the bottle ever breaks, just extract the valve and stick it in a new bottle. This could probably be done on the trail using just a knifepoint.

Give this a try, or express interest in this thread. Perhaps some DIY backpacking supplier (ZPacks, Dutchware Gear) can be convinced to order a box in bulk then sell individual valves at a more reasonable price.

[Nick Smolinske]

This looks awesome. I bet with the combined ingenuity of the forums here we can find a way to get the valves cheaper.

I searched ebay for "duckbill valves" and found a bunch designed for chainsaws – I'm not sure if they would work or be made of safe plastics, but they're cheaper:

http://www.ebay.com/itm/CHAINSAW-DUCK-BILL-CHECK-VALVE-HOMELITE-69451-UP06862-/380354281557?pt=LH_DefaultDomain_0&hash=item588ee1c055

AliExpress is another good place we could search – unlikely to get individual ones cheaply, but there might be someone selling a reasonable quantity there.

EDIT: Here's 10 valves for $20 on AliExpress:

http://www.aliexpress.com/item/Miniature-Silicone-duckbill-check-valve/2022853840.html

Free Shipping, although it'll take a little while to get across the pond.

[David Thomas]

>"combined ingenuity of the forums here we can find a way to get the valves cheaper."

I heard that.

You're looking for a check valve for a fish aquarium. I keep them around for when I need a low-pressure check valve in 1/8" to 1/4" sizes. Doesn't everyone? Here's one for $1.49:

http://www.petguys.com/penn-plax-check-valve-air-filter.html?productid=penn-plax-check-valve-air-filter&channelid=FROOG&utm_source=CSEs&utm_medium=GoogleShopping&utm_campaign=PetGuys&gclid=CLD2yr2AjsQCFYVqfgodCk0Aag

The shipping is going to be more than that, so stop by any pet shop or Petco and see what they have on the shelves.

I'd suggest just drilling or reaming out a slightly under-sized hole and, when the time comes, jamming the check valve in.

as with most things in life, they are cheaper if you get it from China through Hong Kong than through your local retailer. Here are 10 such valves for $2. Yeah, 20 cents each:

http://www.ebay.com/itm/10x-Aquarium-One-Way-Check-Valve-Non-Return-Fish-Tank-Co2-System-Air-Pump-Red-/181435650014?pt=LH_DefaultDomain_0&hash=item2a3e684fde

If one isn't fast enough flow, stick another one in and double the air flow.

[David Thomas]

I really like the very low-profile valve you found. And where you located it, near the mouth of the bottle, keeps that bit off the sides or bottom of the bottle where it could snag more easily.

However, you have to suck against about 6 inches of water column (about 1/4 psi) to get air flow into the bottle. Since bottles are free at the recycling center, and the check valves are 20 cents (and reusable), I'd suggest you try one in the middle of the bottle. And on another bottle, install one at the bottom. See if the easier flowing bottle is to your liking or not.

Trickier to assemble, but a way to keep the check valve near the mouth while having easy flow, is to extend the outlet of the valve (where it enter the water bottle) with 8 inches of vinyl tubing inside the bottle. When the bottle is upright, it would look like a weird dip tube, but nothing would flow (due to the check valve). But when inverted, the air would flow very freely and not require you to suck on the bottle as much.

The other way around that with the Sawyer Mini is to put tubing between the water bottle and the filter. Then the 8-10" of tubing provides the suction needed.

The big improvement is your use of the check valve – as you describe, that lets you use (and maybe multi-purpose?) a rigid bottle instead of using more expensive soft bladders.

[Link .]

Lance Marshall posted the same thing along with a short video he made about 2 years ago Using a rigid bottle on the dirty side of a Sawyer Squeeze

[Bob Shaver]

those are called duck bill valves in the world of valves. Hope that helps you find some for cheap.

[Jim H]

This one you can see the duckbill in the photo, but its $5 for 1:
http://www.amazon.com/JW-Pet-Company-Aquarium-Accessory/dp/B001B4H5NY/ref=sr_1_17?s=pet-supplies&ie=UTF8&qid=1425919863&sr=1-17&keywords=check+valve

This is $8 for 12, but I can't tell if it is the same valve:
http://www.amazon.com/Aquarium-Diffuser-Plastic-Check-Valves/dp/B00H8Q1KD0/ref=pd_sbs_petsupplies_3?ie=UTF8&refRID=0CBMT7BCM15XTRBVY2GQ

Any aquarium lovers know?

[David White]

I picked one up at Walmart this weekend. I'm pretty sure it was $1.89. I'm looking forward to trying it on a Gatorade bottle.

[Jan Miksovsky]

Nick et al.: Many thanks for the pointers to various places to obtain valves more cheaply!

The aquarium check valves look like they have straight sides. One nice feature about the duckbill valve I used is that there's a specific point on it, just below the wide button portion, where the valve is a slightly narrow. This makes it easy for the valve to snap right into place. Once snapped in, it won't easily pop out. A valve with a straight side wouldn't have that feature, but perhaps a smaller hole and a tighter fit could compensate for the lack of it.

[Paul L]

Did anyone ever find check valves that snap into place like Jan’s original valve? I tried the setup with the JW Fusion Aquarium check valves mentioned above and they do work, but as Jan foresaw they can pop out because they are just pressure fitted. Something with a groove that “snaps” into the bottle would definitely be better.

Paul

[Link .]

Jan gives a link to the check valve he used One-direction valve for SmarTube® Cap .

[Author]

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