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Picture of Make your own bite-valve hydration system
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Problem to be solved: like many folks who bicycle or hike, I've used bite-valve, hands-free hydration systems for years. Unfortunately commercial hydration systems include a plastic bladder that is easy to puncture, difficult to clean and expensive to replace. In addition, wearing a backpack that holds the bladder is annoying to cyclists. Far preferable for cycling would be to have a bite-valve system that works with a bottle that sits in the frame-mounted bottle cage. Far preferable for both cyclists and hikers would be to replace the dismal plastic bladder with an ordinary PET soda bottle.

The solution in a nutshell: combine a few purchased components with a purpose-designed Delrin stopper in order to make your own bladder-free hydration system!

The hard problem to be solved: bladders collapse when water is removed and PET soda bottles do not. (Well they will eventually, but not before your ears pop!) Therefore make-up air must be added to the bottle when water is removed. The way to do this is mount a small check-valve next to the drinking hose. The difficulty is that bottle tops are small and figuring out how to fit both a drinking hose and check valve was not easy.
 
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Step 1: Design overview

Picture of Design overview
Design goals:
1. Allow bite valve to be used with PET bottle in bicycle bottle cage.
2. Materials must all be food-safe and easy to clean.
3. Assembly should not leak when shaken or inverted.
4. Parts should be inexpensive and readily available.

Design description:
As shown in the attached drawings, the main effort involves machining a tapered stopper from a delrin rod using a lathe, then tapping 1/8-27 pipe threads in it for a hose barb fitting to attach the 1/4" tygon hose. A check-valve is attached via a short length of 1/8" tygon hose. The 1/8" hose is slipped onto a short length of 0.134" hypodermic tubing that is pounded into a 0.128" hole that is drilled through the stopper. The check-valve is secured to the 1/4" hose via a dab of silicone caulk on the side. The stopper is held securely into a water bottle using an ordinary soda bottle cap through which a hole has been cut using a 3/4" punch. A short length of 1/4" hose is used to attach the acetal quick-disconnect coupling socket with valve, and then a longer run (perhaps two feet) goes from an acetal quick-disconnect coupling plug to the bite valve. The bottle is inserted in the bottle cage and the bite valve is attached to the handlebar with a pair of nylon loop straps.

Email me (alchaiken at gmail dot com) if you would like a DXF format version of the drawings for this project.

Step 2: Parts list: commercial

The project uses some purchased components plus some raw stock materials that must be transformed in a machine shop.

Commercial parts that go into the final product unmodified:

-- CamelBak Big Bite Valve, $5.95 each from Mountain Sports Online, part number 016805
-- White Polyethylene Single-barb Tube Fitting, Coupling For 1/4" Tube , $4.74 each from McMaster-Carr, part number 2808K106
-- 304 stainless steel regular-wall 0.134" diameter hypodermic tubing, $4.85/foot from SmallParts, part number HTX-10R
-- Supravalve Polycarbonate Check Valve, 1/8" tube fitting, $4.50 each from SmallParts, part number CVP-02
-- Smooth-Bore High-Purity Clear Tygon Tubing 1/4" ID, 3/8" OD, 1/16" Wall Thickness, $1.84/foot from McMaster-Carr, part number 5466K14
-- Smooth-Bore High-Purity Clear Tygon Tubing 1/8" ID, 1/4" OD, 1/16" Wall Thickness, $1.58/foot from McMaster-Carr, part number 5466K12
-- Polypropylene Quick-Disconnect Tube Coupling Socket, 1/4" Size, for 1/4" Tube ID, with Valve, $11.77 each from McMaster-Carr, part number 51545K73
-- Polypropylene Quick-disconnect Tube Coupling, Plug, 1/4" Size, For 1/4" Tube Id, W/o Valve, $2.37 each from McMaster-Carr, part number 51545K69
-- Nylon Loop Strap for 1/4" OD, $5.12 per Pack of 100 from McMaster-Carr, part number 8876T13
-- Nylon Loop Strap for 1" OD, $12.46 per pack of 100 from McMaster-Carr, part number 8876T42
-- Black double-sided velcro, available from Fry's or Michael's Crafts, lifetime supply $16.99
-- GE Max5000 Siliconized Acrylic Caulk, available for cheap at hardware stores near you
-- PET soda bottle, available for free from a recyling bin near you! Many brands of drinking water and soda work well with this design, although Coca-Cola bottles have too few threads.

The total cost of commercial parts to make one unit as of January 2008 is about $29 although you could save by purchasing the parts in larger quantities.

For valve-switchable two-tank system, add

-- 3-Way Stopcock With 2mm Bore, US Plastic part number 17223, $44.11 in single quantities.

Step 3: Parts list part 2: raw materials

Picture of Parts list part 2: raw materials
Here I list the parts that are not used as-purchased but must be transformed in a machine shop such as TechShop.

To make the stopper itself:
-- White Delrin Rod, 1-1/4" Diameter, $6.39/foot, McMaster-Carr, part number 8572K233

One-time purchases to make the tooling that holds the stopper during cutting of threads:
-- Alloy 6061 Aluminum Oversize Sheet, .500" Thick, 8" X 8", $30.02, McMaster-Carr, part number 89155K42
-- Alloy 6061 Aluminum Sheet, .190" Thick, 12" X 12", $35.19, McMaster-Carr, art number 89015K31
-- some 8-32 countersink-head machine screws, about 3/4" long
-- some 10-32 socket-head cap screws, about 1" long

Step 4: Tools

Picture of Tools
I fabricated my parts at TechShop in Menlo Park, California. Some of the tools that I mention below I purchased, while in other cases I simply used parts available at TechShop.

Machine tools:
-- metal turning lathe;
-- Bridgeport-style vertical milling machine;
-- band saw.

Hand tools:
-- Small-diameter Hole Punch, 3/4" Hole Diameter, Trade Size 18, $17.91 from McMaster-Carr, part number 3424A51;
-- 1/8-27 NPT tap and tap handle;
-- 1/2" shank micro tap guide, $14.48, MSC Direct part number 95267472 ;
-- No. 30 slow speed drill for brass, $2.98, MSC Direct part number 01388305 ;
-- Letter Q high speed drill, $8.40, MSC Direct part number 01149178 ;
-- Allen wrench set (for 10-32 cap screws);
-- Philips screwdriver (for 8-32 machine screws);
-- Small hammer (for pounding hypo tubing and punching bottle caps);
-- Small tubing cutter (for hypo tubing);
-- Files and deburring tools.

Step 5: Fabricating the tapered stopper

Picture of Fabricating the tapered stopper
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The following discussion assumes some basic knowledge of how to use a lathe.

1. Chuck up the 1 1/4" delrin rod and mount a sharp cutting tool.
2. Using the highest possible speed for this and following steps, face off the end.
3. Set the angle of the cross carriage to 6 degrees so that the small end of the taper will be at the free end of the rod. (Setting the cross carriage angle now minimizes measurement steps later on.)
4. Turn the OD of the rod down to 0.972" on the entire exposed end of the rod.
5. Turn the last 0.56" of the rod down to 0.86".
6. Cut a 6 degree taper on the 0.56" section, leaving the OD of the small end of the rod at 0.76".
7. Moving 0.64" away from the free end, part off the stopper.

Step 6: Drilling the holes and tapping the threads

Picture of Drilling the holes and tapping the threads
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This section assumes some very basic knowledge of how to use a vertical milling machine. It also assumes that you have already fabricated the tooling necessary to hold the delrin stopper during this step, or its equivalent. Fabrication of the tooling is described in Appendix A.

1. Use a deburring tool or file to remove any nub left by the parting-off on the lathe.
2. Mount the stopper in the tooling and tighten down the screws, making sure that the clamp on the top is level.
3. Mount the tooling in the vise of a milling machine, and use an edge-finder to locate its corner, setting both digital read-outs to zero.
4. Use the drawing to center a Q-sized drill bit over the large hole. Drill through.
5. Put a spring-loaded tap guide in the check to keep a 1/8-27 NPT (tapered) tap oriented vertically while you tap threads for the hose barb.
6. Use a #30 drill to make the hole for the hypodermic tubing.

Step 7: Final assembly of system

Picture of Final assembly of system
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In this step, we assemble the components together and test them as a unit.

1. Use a tubing cutter to make a length of hypodermic tubing about 1/2" long.
2. With a hemostat or similar pliers, hold the tubing section about the small hole and gently tap in about 1/8" deep using a small hammer.
3. With the stopper clamped back in the tooling, use a wrench to tighten down the hose-barb fitting.
4. With a scissors, cut a short (2") length of 1/8" tygon hose and slip it onto the hypo tubing.
5. Cut as long a section of 1/4" tygon hose for the draw tube as you will need. Might as well use a long section, as you can shorten it later. Slip it onto the 1/4" hose barb.
6. Place a soda bottle cap threaded side up on a block of wood and, with the small hammer, use a 7/8" punch to make as centered a hole as you can. Slip the cap over the tygon hoses.
7. Blow into the check-valve to see which way it opens. Insert one end into the 1/8" tubing so that make-up air will be able to enter the soda bottle.
8. Place a dab of caulk between the check-valve and the 1/4" hose. The caulk will help to keep the check-valve from falling off when you hit a bump.
9. Holding another section of 1/4" tygon up to your soda bottle, cut a pick-up tube that will just reach from the bottom hole in the stopper to the bottom. Cut the bottom of the tube at an angle. Stick your pickup-tube in the bottom of the stopper.
10. Fill a bottle with water. Place the assembly on top and tighten the threads. Pinching off the 1/4" hose, invert the bottle. Does it leak? If not, success!

Step 8: Installation on bicycle

Picture of Installation on bicycle
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Details of the bicycle installation will depend on the dimensions of the bicycle and whether you plan to put the bottle in a cage or mount it on a rack.

1. Cut a piece of 1/4"-diameter tygon hose that's long enough to reach from your stopper to the bottom of your bottle. Cut both ends at an angle so that the draw tube won't stick on the bottom. Stuff one end of the draw tube in the hole on the bottom of the stopper.

2. Mount your stopper and draw tube assembly onto a bottle and place it into the frame-mounted bottle cage. Repeat with a second bottle if desired Doesn't that look cool? Isn't being a nerd fun?

3. Insert a quick-connect with anti-siphon valve into the tube at the top of the stopper. Insert a matching quick-connect into a long section of 1/4" tygon and snap the two fittings together. Cut the long tube to the desired length for the draw tube. Mount the bite valve on the end.

4. Put a 1/4" cable clamp around the draw tube and position it over the handlebar. Put a larger cable clamp around the handlebar and connect the two cable clamps together using a screw. You may want to use a piece of inner tube to keep the larger cable clamp from slipping on the bar. Once the draw tube is attached, you can pull the tube back and forth through the cable clamp to adjust the length.

5. Unsnap the draw tube from the first bottle and use more quick-connects and 1/4"-hose to make an extension tube for the second bottle. Use velcro or cable clamps to attach the extension tube to the top tube of the bike.

6. Fill your bottles and go for a ride! Riding is why we went to all this trouble, remember?

Step 9: Desired improvements

1. Make the plastic parts in one piece using an injection molder. I know that there are services like Proto-Mold that will do small injection-mold runs, but I don't want to spend a lot of money, and would like to play with the injection molder myself. Anyone here in the San Francisco Bay Area have an injection molder that will accommodate a food-safe plastic?

2. I've added a three-way wye valve that will allow me to switch between two bottles with a twist of a knob while pedalling hard. I'm using this most excellent nalgene stopcock but it's very expensive. Anyone know of a similar food-safe product at a more reasonable price?

3. Make it easier to pour powders and squirt gels into the bottles . . . the small opening compared to ordinary bike water bottles is a disadvantage.

4. Find cheap replacements or less expensive sources for the pricier components.

Step 10: Claims (for legal purposes)

Picture of Claims (for legal purposes)
I wish to publish this invention with the Creative Commons license and wish to make explicit that I claim the following novel aspects:

1. a bite-valve hydration system that works with an ordinary soda bottle;
2. furthermore, a system that works with a bottle placed in a bicycle bottle cage;
3. a system that works with a bottle strapped to a bicycle rack;
4. a system that utilizes a check-valve along with a container that does not collapse when water is removed;
5. a system that utilizes a pick-up tube that allows fluids and gels to be drawn from the container bottom;
6. a system where the bite-valve tube is attached to the handlebar, for example with a cable clamp;
7. a system for a bicycle where tygon tubing is routed along the bicycle's top tube, for example with velcro;
8. a system which utilizes quick-disconnect tube couplings to allow easy bottle change;
9. a system which utilizes a quick-disconnect tube coupling with a valve to prevent leakage and provide an anti-siphon-back feature for the tube.

This invention is Open-Source Hardware and has been reduced to practice. Its invention by me has been observed by dozens of members of TechShop and the Almaden Cycle Touring Club. The system was described and demonstrated to a meeting of the Make:SF group on January 7, 2008. Any attempt to patent a bite-valve hydration system that works with a soda bottle and is mounted on a bicycle as described above should be blocked by the Prior Art represented by this Instructable.

The photo is from the January 7, 2008 TechShop demo and was taken by Sherry Huss of O'Reilly.

Step 11: Credits and acknowledgements

Two-dimensional CAD drawings were made using QCad. I took a lathe class from Jim Newton and a mill class from Alec Aisner. Many folks at TechShopTechShop offered valuable advice and encouragement, especially Lloyd Stafford and Chris Tacklind. I also appreciate the expertise of Jim and Paula Vanderpool at Dan-Mar Tool in San Carlos, CA. Special thanks to Barry Burr for suggesting the silicone caulk and the bottle cap punch.

Step 12: Appendix 1: the hiking version of the homemade bite-valve system

Picture of Appendix 1: the hiking version of the homemade bite-valve system
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The 1 psi (1/15th of an atmosphere) pop-off valve is not adequate to allow a pickup tube to draw from the bottom of a vertical, upright two-liter soda bottle for hiking purposes. The solution is to invert the bottle and draw from the bottom. Drawing from the bottom requires no pickup tube but it does mean that the pop-off valve is best kept protected inside the bottle, where it won't get knocked off. A hiking version of the bite-valve system is therefore the same as the cycling version except that

1. the hypo tubing and pop-off valve are on the inside;
2. there's no pickup tube;
3. it's more convenient to use a right-angle poly hose barb.

For the 2-liter horizontal bottle attached to the bicycle rack as shown on the first page, I used an external pop-off and a draw tube, although tilting the bottle a bit makes the draw tube unnecessary.

Step 13: Appendix 2: Maintenance

I don't clean the bottles or tubing used with this system: I just throw them away and replace them. However, in order to keep the stoppers clean, I do flush them with warm soapy water and then rinse them after every ride where they are exposed to sugary sports drinks. After rides where I drink water only, I just drain the system down and let it dry.

I end up replacing the bottles and tygon hose after perhaps 50 hours of use. Every 200 hours or so, the check-valve begins to look a bit nasty, and I replace it as well. When that happens, I soak the whole stopper assembly in a dilute bleach solution, then rinse and dry well.

Step 14: New two-tank mixer and switcher valve

Picture of New two-tank mixer and switcher valve
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The recent addition of the U.S. Plastics valve makes possible one-handed switching between the two tanks. The previous method of disconnecting one quick-disconnect and connecting the other required two hands and was too tricky for me to do while riding. Also, the valve allows mixing of the two tanks! Sometimes I run one tank with water and one with sports drink and switch back and forth.

The second photo is a detail of the valve showing how I've stretched a piece of old inner tube over the bottom half of it. The valve tended to chatter on the top tube during fast bumpy descents, but the inner tube section solves this problem, and I just happened to have an old inner tube on hand.

Unfortunately, the valve costs more ($44) than the rest of the system combined ($29)! If someone knows of a cheaper source for a 3-way stopcock, I would be pleased to learn of it.
SeanD42 days ago

You'll spend more time and money making it than using it. Stop being cheap and "eco-friendly" and just get a decent, commercial hydration system. Camelbacks are made in China now, so they're affordable to even tree huggers.

jallen162 months ago

Looks More Like A Mobile Meth Lab LMAO

You could of just poked a small micro hole on the top of your water bottle instead of making that useless one way valve, from scratch, haha. But I can't do that, that's really hard to do, so congratulations. But next time, you could find simple solutions for simple problems, it's okay if it drips a few drops on the whole trip, it's just a easier way to do it.
chaiken (author)  stealthsilent1 year ago
The best solution, as always, depends of the use case. If the tubing length is short and spills aren't a problem, then a hole in the lid is fine, I'm sure. A wet sleeping bag is unacceptable to me in cold weather though, so I like a water-tight seal. Also, if the tubing run is long, a system that will hold a small vacuum allows the tubes to stay filled after the first sip. For strenuous cycling, the convenience of having to move the liquid 1 cm to drink instead of through the whole length of the tubing every time is worth the extra initial assembly trouble.
speter51 year ago
Hi Chaiken, we like your solution! We were thinking about the same thing. Check out our Convertube. It turns every bottle into a hands-free hydration system: http://sourceoutdoor.com/hands-on-systems/22-convertube.html The kit contains adaptors, tube, valve, dirt-shield. Have fun!
chaiken (author)  speter51 year ago
Indeed, your system looks virtually identical. Mine is now about 5 years old and I couldn't find any similar commercial products on the market at the time. I now have a better version using stainless steel hypodermic tubing, silicone stopper and metal wide-mouth soda can, but have been too slow to post details.

Best wishes,
Alison
ilpug4 years ago
This is very high quality, and i can see you put a lot of effort into this, but it all seems a bit complex to me just for the sake of getting a drink while on a bike.
speter5 ilpug1 year ago
Hi ilpug, here's a shortcut - same result: to turn (almost) any bottle into a hands-free hydration system: http://sourceoutdoor.com/hands-on-systems/22-convertube.html
I like this 'cause I don't have to have only water. I know I should, but I need sugar, and camelbaks will die with anything but water.
nice 'inble, but 'platypus' hoses have a thread that fits soda bottles already, and if you are dis satisfied with the blader, it would be an easy conversion to use your attatchment method
timtak3 years ago
I am looking for a dual hole (straw plus valve) system like this even on a normal (non-PET) bike bottle because I want to be able to squirt several times into my mouth.

With the usual O-ring system one has to remove the bottle from ones mouth and wait for the bottle to reinflate through the same hole as you are drinking from but with this one can let air come into the bottle through the check valve and squirt again pretty much immediately (if the valve hole is fairly big and the bottle has a strong elasticity as PET bottles do).

I wish this product were commercially available!

Or is it? Does the camelbak bike better bottle with "bite valve" have this type of two hole (drink plus check valve) system?

The sipway looks okay but I would rather do without long straws.
chaiken (author)  timtak3 years ago
timtak, you should be able to make a second hole and put an up-to-air valve on any container. The technique of using a few-mm piece of stainless surgical tubing attached to a similarly short piece of tygon house going to an up-to-air valve should work with any hard plastic container. If you drink water, I recommend putting the valve inside, as there's less chance of knocking it off. If you drink other beverages with sugar, you can still put it inside, but you'll have to clean it (bleach or Efferdent) or replace it frequently.

Best wishes,
Alison
who has an entirely different superior design using RockStar cans that she's too lazy to post.
timtak chaiken3 years ago
Okay, thank you for your reply and encouragement, I am having a go now.

There are valves in the kerosine pumps sold at local "dollar" stores and I have attached one to a water bottle sold at those stores.
chaiken (author)  timtak3 years ago
Be sure that any components you buy are chemically compatible and food-safe. You don't want to have a metal part dissolve in acid sports drinks for example. A part made for kerosene near beverages sounds a bit scary to me.
timtak chaiken3 years ago
The plastic kerosene pump looks to be made of the same sort of plastic as the bottle is made out of. I will take it easy on the drinks.

Since I can't purchase yours and I am bad at making things I would probably order a sipaway or sipstream but the postage is prohibitive to Japan.

By the way there is, I think, now a commercial version that takes commercially available PET bottles.
http://www.amazon.com/Blue-Desert-SmarTube-Hydration-System/dp/B000GM6LWS/ref=sr_1_2?s=sporting-goods&ie=UTF8&qid=1317193623&sr=1-2
The reviews are not good though so I am sure yours is better.
timtak3 years ago
Oops sorry, I see that this does have long straws and is very similar to the three products (sipway, oasisone-twelve and never reach) above.

I think that it would be cool to have a normal bottle cage bottle version just for the convenience of being able to such/squirt continuously without having to wait for air to get back into the bottle.
theprophet25 years ago
I know it is great fun and all making your own bite valve, but surely it would be easier to use a commercially available bite valve in plac e of a home made one?
chaiken (author) 5 years ago
It's true that there are now commercially available bite-valve-and-bottle-cage solutions, although I don't believe that there were any when I began the project.   However, none of the commercial solutions that I know of are compatible with bottles that are free.

It's true that my solution doesn't keep the drink cold, although the user can always put ice in the bottles or freeze them.    I usually purchase cold drinks at stores and finish them quickly, so I don't really care.     Not having a sweaty backpack on more than makes up for warm drinks.

The suction force needed to draw up the liquid is small due to the anti-siphon valves.   Once the tube are filled, they stay filled and then the bite valve even tends to drip when it's draped over the bars.

I actually have a completely new design using aluminum Rockstar cans that I have finished implementing yet.

Best wishes,
Alison
zellmer6 years ago
I have been trying to find a manufacturer of the "bladder" with screw top, but I'm having a VERY hard time. I want a small bladder system, about 8 oz. Do you have any contacts for me? I want to stay USA.
 im  not sure exactly what you are talking about but you may be looking for something like a platypus bladder.
first the amount of work you did here is amazing. you have made something very advanced, the one problem that i see with this disigne vrs the bladder is the amount of sucking force needed. I used to use a bladder when hiking. (i now just use water bottles.) At least in my hiking backpack when i released the bite valve there was very little to know force needed to draw watter up because of the pressure on the bag.it seems to me like it would take alot of effort to bring water from these bottles to your mouth.
BrickMaster5 years ago
thanks for the plans. Interesting to see what would go into building your own.  Looking at Build vs Buy & Time vs $$$... I think would would go with one of these:

www.oasisone-twelve.com

www.sipaway.com

www.neverreach.com

-Thanks
kwalian6 years ago
Is it safe to use vinyl tubing in a DIY hydration system? I got some from Ace Hardware but my parents said that it's probably not food-grade.
chaiken (author)  kwalian6 years ago
To be honest, I don't know what kind of tubing is safe. I just always use components that say "beverage grade" or "FDA approved" or some such. You'll notice that the parts listed on my Instructable are all so labeled, except for the stainless steel tubing, which I'm assuming is okay. Of course the fact that some plastic products are labeled "food grade" implies that others are not.
you know... take a 3 liter soda bottle, put 2 holes in the cap, feed the hose in one hole, and another into the other hose, put a fish tank anti-siphon air thing on each end, and you will have the air infeed you need, and the water out that you want without the ear popping... I am currently working on one myself.
thats what i did
chaiken (author)  infernisdiem7 years ago
Does your system leak when inverted? Mine doesn't. Also, once you fill the hose on mine, it stays filled. And I have enough vacuum (about 1 psi) that I can pull goos like Hammer Gel up through the hose. So yes, you can make a simpler system with the same gross features, but it would be hard to make one that's simple and works as well without an injection molder. I wish that TechShop (http://www.techshop.ws/) would get an injection molder!
Actually the original that I made was all friction fit, and did not leak when inverted.
finnster7 years ago
No offense but thisis overcomplicated compared to mine (mine is a bite valve from a water bottleconnected to tubing that connects to two-one liter bottles).
theRIAA7 years ago
wow.... i wasn't expecting it to be so.... damn expensive and complicated.... I saw the old bike and assumed you were doing something cheap and super simple to make... I guess you're thinking of making this into a commercial product?
chaiken (author)  theRIAA7 years ago
wow.... i wasn't expecting it to be so.... damn expensive and complicated....

Me either. Suggestions are welcome! $12 of the cost is the
anti-siphon valve that means that the bottle can inverted without
leaking and that the hose, once filled, stays filled. Without that,
the cost would be lower, but the system would be much less sweet to
use.

It should be possible to make a simple, cheap, injection-molded
version, but TechShop hasn't gotten an injection molder yet.

I have other Instructables that I'd like to post that are simple and
cheap but I need to finish this one first.

I guess you're thinking of making this into a commercial product?

No actually. I am a Linux user and believe in Open Source. I
would like to share my invention and prevent others from patenting it.
Thanks for making Instructables available for this purpose. If
you would suggest a different license, please let me know!

I hate having to suck the water out of my hydration bladder. Soda bottles are designed to withstand an amazing amount of pressure for what they're made of... Why not add an inline tee with a schrader valve so that you can use your tire pump to pressurize your water? You would only need a few pounds pressure at most. Granted, your bite valve may have to be redesigned to sustain that pressure, but I think it would be a much more pleasant way to drink. Also, semi-trucks have threaded brass (or chrome plated brass) valve stems that are inserted into the rim hole, and then a nut is used to secure the stem in place. One of these could easily be used as a tap in a soda bottle lid. As they are sealed with rubber washers, this would be a bullet-proof way to make a very stout dripless tap. Oh, and make sure you take out the valve core! :o)
dudes.....you can buy a camel back backpack for10 or 20 dollars and it would keep your drink colder...
WOW! Looks like a lot of work! But still, I bet it's worth it, nice job.