The Incredible Shrinking Water Bottle

UPDATE: Primo’s VP of Marketing Responds to Incredible Shrinking Water Bottle
Reader David wrote in to show us the transformation of his incredible shrinking water bottle. The bottles used by Primo bottled water are made from plant by-products which degrade easily compared to normal plastic, making them more eco-friendly. However, as David found out, they shrink to nearly half their size when exposed to sunlight and the heat from inside a car which could easily result in a watery mess. David’s letter and photo, inside…


I recently purchased a case of Primo bottled water. Like other products,
it’s trying to a niche. Their spin is that the plastic in the bottle is
made from plants, not crude oil. Additionally, they claim the water tastes
just as good as the national brands. BUT the thing you aren’t told is that
the bottle shrinks!

I left a bottle in my car while I was at work (I park in an open lot). When
I left work and got into my car, I noticed that the bottle was half its
original size. The bottle shrank after a few hours under the Houston sun.
Perhaps plastic made from corn by-products is not as durable as plastic
from petroleum. Whatever it is, I am concerned. If the bottle was full and
it shrank, it could have exploded from the pressure. Or it could have
gushed out as I was opening it. Because the plastic is so sensitive to 100
degree heat, it doesn’t serve its purpose very well. And, this probably
means that toxins could be leaking out from the plastic.

Buyer beware!

I have enclosed a picture that compares the original bottle with the
shrunken version.

Thank you,


Degradable bottles seem like a good idea, we just don’t want them degrading inside of our cars.


Edit Your Comment

  1. magic8ball says:

    There are other concerns with biopolastics as well – many of them only degrade in very specific conditions which require special facilities to process them. It’s not like you can just toss them into your compost or the landfill or whatever and they’ll break down on their own.

  2. matthewgerber says:

    Must’ve been the Grocery Shrink Ray!

  3. Kajj says:

    Wow, that’s actually pretty cool. I’m going to keep an eye out for that brand.

    Oh crap, have I just been virally marketed?

  4. 100 degree heat in a car under a Texas sun? I’m guessing it was quite a bit hotter than that. Don’t we hear every summer how you can fry an egg inside a closed car in the sun? Of course, at those temps, even a super strong aluminum can can and will burst open.

  5. doctor_cos wants you to remain calm says:

    Was the bottle full or mostly full when it shrunk? I would think the water in the bottle would act as a heat sink and protect the bottle (much like holding a match to the bottom of a styrofoam cup filled with water).
    Perhaps some gubbamint money to do a study is in order here :)

  6. WiglyWorm must cease and decist says:

    @doctor_cos: Holding a match to the bottom of a cup, the heat will disipate into the water and out into the air. Locked inside a hot car, the car, bottle, and water will all eventually reach the same temperature, the heat will have nowhere to go, and the end result will be the same.

  7. Toof_75_75 says:

    “Grocery Shrink Ray” on crack! Usually it only shrinks the packaging by a few ounces! haha

  8. raremoth says:

    I would definately be most concerned about whatever toxins become released. I have heard that Cheryl Crow thinks her breast cancer may of been caused by drinking water left in a plastic bottle in a hot car.

  9. Angryrider says:

    Great… Now it’s less safe to drink bottled water. Those chemicals have to go somewhere.

  10. That’s kind-of awesome.

  11. zigziggityzoo says:

    @Git Em SteveDave is a poor substitute for LindsayJoy: Heck, here in MI I’ve had cans burst open in my car. Happened 3 weeks ago. Not fun.

  12. @Toof_75_75: No, now it’s shrinking packages AFTER you buy them.

    It’s in ur hom, shrinking ur fud.

  13. Nytmare says:

    Water bottles are made from shrinky-dinks!

  14. EndlessMike says:

    The water certainly wouldn’t gush out upon opening. Water doesn’t compress. Most likely, it would just break somewhere and you’d get a little water (no more than 16.9 fluid ounces!) on your carpet and your car would be a little steamy when you open it. Nothing major.

  15. Sidecutter says:

    @nytmare: Soylent Water Bottles. They’re shrinky-dinks I tell you! SHRINNNNKY DINNNNKS!

  16. PencilSharp says:

    Considering the amount of heat that is usually generated by degrading landfill stuff, I would think that this is by design. Then again, a little marketing could make this a selling feature…

    Hey, it worked for Diet Coke and Mentos…

  17. tman996 says:


    Right. Water is only very slightly compressible. So how could that bottle have shrunk that much without bursting or at least leaking out the top? And why didn’t the threaded section shrink? Skeptical…

  18. unchi says:

    a few years back, there was a water bottling company in colorado who made water bottles using bioplastics. publix picked them up and i bought a few 6-packs for a few weeks until i guess they went under. anyhow, there was a warning label on those bottles stating that you had to keep the bottles COOL. the corn-based bioplastic was designed to decompose when applied with around 350 degrees fahrenheit. the only problem is i don’t see this warning stated obviously on primo’s website and they seem to have this problem too. this has nothing to do with a poor product, but more to do with poor labeling and not educating your consumers on the limits of the container.

  19. The_Gas_Man says:

    And now we see first hand the fallacy of “eco-friendly” (self?)disposable packaging. It’s generally more expensive, you can’t store it for long periods of time, you can’t even leave it in your car. There’s no expiration date or instructions on safe use or storage of the product (probably because the manufacturer doesn’t know either).

    Can’t we come up with something that takes a more reasonable amount of time to break down? I don’t know, two years maybe? Five? Certainly that would be sufficient compared to hundreds (thousands?) of years for normal plastics.

  20. TheAlphateam says:

    You would also have to take in consideration the amount of energy it would take to heat the water. I would think you would also have to heat the water to the same temp to melt the bottle. You can do a simple experiment yourself. Take and suspend a piece of copper tubing (or any metal for that matter) in a piece of paper. You would hold each edge of the paper and the tubing would be in the middle. You would have a tear drop shape in profile. Then take a flame and place it under the tubing. The paper will blacken, but it won’t burn. Not until you reach the melting point of the metal.

  21. chrisjames says:

    Even if it wasn’t shrinking, you can be sure that material from the bottle is leaking into the water. That’s just what happens when a container meets a liquid.

  22. unchi says:

    i picked them up in the hot georgia sun of atlanta. so the warning labels were obvious (like they should be for say texas)

  23. Coles_Law says:

    My guess is the water bottle was nearly empty-you can see the water level in the small bottle. I don’t think this isa trick either-if you look closely, the base of the shrunk bottle is wider than the middle-I’ve never seen a bottle sold like that.

    As for the threaded section, it may have been a different plastic. At the least, it’s a thicker plastic. Come to think of it, that would explain why the base didn’t shrink as much either.

  24. Coles_Law says:

    @TheAlphateam: not necessarily the melting point. Once the metal heats to the flash point f the paper, it’ll go.

  25. davekoob says:

    And here I thought this would be an article about the grocery shrink ray!!!

  26. AmbroseP says:

    Well, if you’re buying bottled water in the first place…

  27. I would like to bring bottles made out of this to the airport.

    “Sorry, that bottle is larger than 1.6 ounces”

    “Ok, just a sec.” *heats up bottle*

    “Is that better now? We can fly safely.”

  28. bver100 says:

    I remember 6 years ago when i was in middle school kids used to take the water bottles we got at lunch and bring them to the hot water dispenser and fill them. They’d shrink almost instantly to half their size. I think its just general for some types of plastics–shrink under heat?

  29. basket548 says:

    @ Original poster:

    Good information to have (I certainly wouldn’t want anything leaking into my car!), but “And, this probably
    means that toxins could be leaking out from the plastic.”

    Assuming much there? On what basis are you making this claim?

  30. NotATool says:

    @basket548: Umm…on the basis that the bottle has heated to the point where it’s becoming severely deformed. That’s the first thing I thought of when reading this…who cares about water all over your upholstery, I’d be worried about what the bottle might be leaching into my water.

    You don’t need 100% scientific proof here, just a reasonable dose of caution…

  31. basket548 says:

    Still no basis. Even a reasonable dose of caution doesn’t seem to indicate that. What manufacturer would EVER release a product that leaks anything remotely harmful when subject to normal environmental conditions?

    Also, just because something shrinks and ‘deforms’ doesn’t mean that it’s leaking something dangerous. Think of it as a plastic balloon. Same exact concept.

  32. mthrndr says:


    that’s awesome

  33. colinjay says:


    “What manufacturer would EVER release a product that leaks anything remotely harmful when subject to normal environmental conditions?”

    Google “Nalgene” and “BPA”

  34. cpt.snerd says:

    hoooooolyyy crap!
    i want to buy it just to see it happen… with a full bottle!

    Instead of freezing the water and making it burst out of the normal container, this is the container shrinking and making the water burst out! Fun!

  35. basket548 says:

    Good point, however, BPA is far from a proven, well, anything. Everything and its mother is getting linked to cancer these days, and the point I was trying to make was that no manufacturer would knowingly release a product (especially one marketed as ‘organic’-like) with that sort of an issue.

  36. bilge says:

    Most plastic in the US is made from natural gas, not oil.

  37. kjherron says:

    Bottles like that are made by warming the plastic, then inflating it within a bottle-shaped mold. When the plastic cools, it keeps the shape of the mold. But it’s under some of tension; heat it a bit and it will contract. You can make regular two-liter bottles shrink the same way, by heating them with steam from a tea kettle.

    I agree that if the bottle were full of water, it wouldn’t have shrunken like that, though it might have deformed a bit.

  38. Dervish says:

    @basket548: I agree. Since the main purpose of the plastic is to bidegrade in this way, I’m guessing it was designed so it wouldn’t leach poison into the environment. Plus, I’m willing to bet that this pretty common scenario was covered during the product testing.

  39. qhobbit says:

    This is a common effect in bottles that a made from blow-molding. The bottle starts out as a plastic tube called a parison, which looks like a test tube. It is literally blown out with air pressure into a bottle shaped mold. The stretching, as the bottle takes its shape, will orient the polymer molecules in the plastic. The bottle is cooled, which freezes the polymer molecules in place. If you raise the temperature the polymers unfreeze and return to their original position, making the bottle return to its original shape.

    The screw cap part doesn’t shrink because it was never stretched in the blow-molding process. You can try this yourself by holing a match under an empty water or soda bottle. Any bottle with the recycle code of “1 PET” of “1 PETE” should shrink some under heat.

    The newer plastic likely isn’t biodegrading but simply undergoing the same process at a lower temperature.

  40. Ubermunch says:

    @Git Em SteveDave is a poor substitute for LindsayJoy:

    Sorry… but there’s no way a can would explode in a hot car. Worst case is the dent in the bottom of the can (also known as the “kick” or “punt”) would be pushed out. That’s exactly what it’s designed to do. I’ve had full cans in a car at 150+ degrees and they we undamaged.

  41. sketchy says:

    @chrisjames: and to the author:

    Because the plastic is so sensitive to 100 degree heat, it doesn’t serve its purpose very well. And, this probably means that toxins could be leaking out from the plastic.

    MmmmHmmm. This belief is based on what, exactly? Do you even know what the bottle is made of that might be toxic?@

    href=”#c6857155″>colinjay: BPA in cans and bottles in not unsafe. Both the FDA and Health Canada have shown (using science, of all things) that there is no danger presented by the BPA in cans and bottles.

  42. Ubermunch says:


    Are you sure they had not already been damaged. If a can has already been dropped and the can dented, they can then be prone to exploding when heated. But an undamaged can should do that.

  43. mariospants says:

    An intelligent bottle: it shrinks to maintain that “still full” look!

  44. Ein2015 says:

    Growing up in Houston, I can tell you that the heat will probably destroy ANYTHING left in your car. Seriously. :(

  45. mad_hatter_md01 says:

    I love how no one has noticed the Deer Park bottled waters at all. They redesigned those too to have a smaller bottle size but look the same hight as the older bottles.

  46. xwildebeestx says:

    It won’t burst if it has water in it. The water pulls away most of the heat from the plastic and also reinforces the bottle. I’ve never seen this particular brand of water, but I’ve had plenty of opportunities to test similar ones in the pressure cooker that is my car in summer in Phoenix.

  47. @Ubermunch: Sorry… but there’s no way a can would explode in a hot car.

    I’ve seen the aftermath of a heat-related soda can explosion in the Arizona desert. [] has stories of a few more.

  48. HuntersCanvas says:

    We have a number of coffee shops here that serve their cold to-go drinks in corn-based plastic cups. They shrink like this when you leave them in the car.

    It’s still better than oil-based plastics, so if you want a bottle to hold onto that won’t shrink, buy a Sigg bottle.

    My only complaint is that I can’t recycle these cups (number 7) and they just get tossed if you don’t have a compost disposal bin around (which is basically everywhere).

  49. @Ubermunch: Well, speaking from personal experience, for which I had a stain on the roof of my car until I got rid of it, yes, they can. The can in my question HAD popped out the bottom. It then failed on the top seam/lip of the can, which dented out as well. Given my story, the other one below mine, and the link above, I am going to say that a can CAN burst/explode in a heated car. Now I believe my can was a Diet Coke, so if anyone can further expand on their stories, maybe a certain kind of soda has a propensity to crack. Now that I think about it, Diet Coke seems to be very energetic, especially when combined w/Mentos.

  50. lannister80 says:


    A can of soda can most definitely explode in a hot car. I left a sealed can of Sprite near the rear window of a car in 90+ degree heat in Toledo, OH a few years ago. Walking back to the car, I noticed that it looked all “foggy” inside. Of course, it was really that the entire inside of my car was coated in sugar-water, some of which had browned/carmelized and dried to the ceiling, carpet, etc. Not fun.

    The can looked like it had been torn open very violently, length-wise. The bottom indentation was pushed out as well.

  51. TheName says:

    I love the “this ‘eco-friendly POS almost broke in my car in the parking lot at work!'” complaining. How about a nice, more eco-friendly, refillable water bottle along with the bus? Forget the “buy into the green” and just live a little more green.

  52. NotATool says:

    @basket548: I respectfully disagree. How do you know if the plastic bottle has undergone any heat treatment testing? Just because the label says it’s biodegradable doesn’t mean it’s 100% safe, even in hot temperatures.

    I personally would not want to ingest water from a deformed bottle. To me that seems like reasonable caution. Kind of like not buying a dented can at the grocery store. It may or may not be OK, but I don’t want to be the guinea pig.

  53. stevegoz says:

    @Ubermunch: My last car — and the massive stain all over the passenger-side front seat and upholstery underneath the roof (do cars have ceilings?) say otherwise. Had a can of Coca-Cola blow up in Chicago.

    Also learned that waxy paper cups from fast-food joints will melt unpleasantly and leak all over when left in a hot car for days on end….

  54. witeowl says:

    @Git Em SteveDave is a poor substitute for LindsayJoy: Yep. Most likely it was much higher than 100 degrees. The lack of understanding of exactly how hot cars get is the cause of too many pet and child deaths. I’m OK with a waterbottle casualty.

    (Oh, and before I forget, on the toxicity issue: “OMG! There are chemicals in my water!” Must I again bring up the frightening reality of dihydrogen monoxide?)

  55. donkeyjote says:


    Seriously, that is cool looking.

    Even the cap shrunk along with the mouth.

  56. Dervish says:

    @NotATool: The plastic has probably undergone heat testing at multiple points – I’d guess, at least, at the original manufacturer (which uses the data to ensure that the product conforms to their specifications/gov’t regulations) and again at the bottler (to ensure that they’re getting material that conforms to their standards).

    Additionally, corn-based plastics like this are rated as “compostable plastic,” an ASTM standard that states (among other things) that the material must leave no toxic residue and must break down into carbon dioxide, water, and biomass.

    I do think it’s ironic that their selling point is biodegradable plastic, when bottled water is inherently environmentally inefficient.

  57. donkeyjote says:

    @witeowl: Don’t! The people can’t handle the truth!

  58. driver905 says:

    Well I would have to guess that he just slid the label off a bottle then placed it over a smaller bottle and is now enjoying a good laugh at all the discussion. I just have a hard time believing a plastic bottle would shrink so perfectly and evenly in all dimensions, yet have the mouth size stay the same to continue holding the threaded cap, or that the cap would shrink the same as the bottle. The shapes of the bottoms don’t exactly look the same either. Just my skeptical opinion, I could of course be wrong. Someone else buy some of this stuff and run a test. Also, as others already pointed out, a car parked in the sun in Texas gets a LOT hotter than 100 degrees inside.

  59. TheDeadEye says:

    @driver905, donkeyjote: I call shenanigans as well.

  60. JennaBelle says:

    I’m in Michigan and I have to agree with zigziggityzoo, I’ve had cans of diet coke explode in both my hot car and my freezing cold car. Neither are very fun to clean up.

  61. Vulpine says:

    Why is it that nobody even questions whether or not these are even the same kind of bottle in the photo? There are too many variations between the two bottles to seem all that realistic. Most visibly the bottom of the smaller bottle appears to be from a completely different mold and possibly even a different material altogether, like a glass fruit-juice bottle as compared to the plastic water bottle. Even the shape of the shrunken bottle has very little similarity to the larger bottle.
    The label actually seems to confirm this issue because even if it’s a different kind of plastic, it should have distorted more than appears in the given circumstances.

    All in all, while I won’t say it didn’t happen, I also have to say I’m extremely skeptical of the whole story. I have no experience in ever seeing this kind of shrinkage despite buying water and other consumables and leaving partially or even completely empty bottles in my car for days during a hot summer.

    As for the “exploding aluminum can” comments, Discovery Channel’s “Mythbusters” has debunked that particular story very graphically, per this link: []

    While I don’t deny a car gets hot, conditions such as needed to cause such an effect need to be more extreme than evidenced in this discussion. Possibly the one mitigating factor was whether or not the car involved was black rather than some other color, at which point it could absorb much more heat and maybe have enough additional effect to cause the stated shrinkage.

  62. synergy says:

    Maybe it’s a depth-perception trick. ;)

    What happened to the ripple part on the bottom of the bottle?

    Another idea, hot air could leak out through the cap, depending on how tightly it was closed, and didn’t pop.

  63. Vulpine says:

    Of course, you all realize you are being legally poisoned by your water anyway. Has anybody bothered to look into the hazards of fluoride in your drinking water? How about the chlorine salts? Drugs? All of these have been found in tap water around the country and some of them are legally mandated.

    What’s a little plastic in your water compared to all these other chemicals?

  64. @witeowl: Must I again bring up the frightening reality of dihydrogen monoxide?

    Seriously, that stuff is the worst. It ought to be banned.

  65. unme says:

    corn-based bioplastic
    another piece of tech competing with me for food

  66. privateer says:

    Here in Seattle, land of all things green, many shops have started using the “100% Compostable” cups (as well as the tops for them). Another big label trumpets “Made From Corn.” But in tiny letters on the bottom of the cup, it adds, “For Cold Drinks Only.” No other warnings of impending shrinkage or heat-related doom.

  67. rellog says:

    @sketchy: Wrong. Health Canada has listed BPA as dangerous and are seeking to list it as toxic. And let’s be honest. We can’t trust anything coming from the current administration’s departments right now. Censorship of actual scientific data by corporate lackeys installed by the Bush regime has seen to that.

  68. Dervish says:

    @rellog: Just playing devil’s advocate here (I haven’t read any of the research myself) but German and Japanese agencies – as well as the EU’s Food Safety Authority – seem to think that the toxicity studies don’t hold much water. And I know that the EU tends to be pretty strict about this stuff.

  69. RabbitDinner says:

    Grocery Shrink Ray in stealth mode-shrinks after you buy

  70. TobiasPhilemon says:


    Thanks for alerting us to David’s discovery about Primo in “The
    Incredible Shrinking Water Bottle” post. Also, we want to thank David
    for making the simple choice of choosing Primo over other bottled

    As your readers have pointed out, many beverage bottles alter when
    exposed to high heat. Because Primo bottles are made from a renewable
    plant-based natural plastic that is better for the environment that
    oil-based bottles, in some instances, exposure to high temperatures can
    alter the shape of the bottle. As with all beverages, we recommend
    storing Primo in a cool place. In addition, there should be no worry
    that any chemicals can leach into the Primo water. Rigorous testing
    indicates that regardless of temperature, there is no known leaking of
    chemicals from Primo’s natural, petroleum-free bottle to the water
    inside. Primo single-serve bottles are also 100% BPA free.

    Thanks to your story, we will update the “frequently asked questions”
    section on our Web site at
    to clarify these points.

    Tim Ronan

    Primo Water Corporation

  71. doctor_cos wants you to remain calm says:

    @WiglyWorm: Aaaaah. Thank you for that explanation.

  72. Cybrczch says:

    @driver905: I just have a hard time believing a plastic bottle would shrink so perfectly and evenly in all dimensions, yet have the mouth size stay the same to continue holding the threaded cap, or that the cap would shrink the same as the bottle

    The amount of plastic used is a lot thicker at the mouth of the bottle – this can be demonstrated on any plastic drink bottle – squeeze the middle and see how flimsy the plastic is there, then take the cap off and squeeze the mouth of the bottle. A lot thicker. The thinner parts would be affected by the heat first and show more obvious shrinkage, with less structure to keep them from shrinking.

  73. oldheathen says:

    LOL @ Sidecutter’s “Shrinky-Dinks!!!” Damn we’re old.

  74. ShatarupaHizee says:

    Just for the record, from

    Will Primo bottles change shape in high heat?

    Primo bottles are made from a renewable plant-based natural plastic that is
    better for the environment than oil-based bottles. But like other plastics,
    in some instances, exposure to high temperatures can alter the shape of the
    bottle. As with all beverages, we recommend storing Primo in a cool place.
    In addition, there should be no worry that any chemicals can leach into the
    Primo water. Rigorous testing indicates that regardless of temperature,
    there is no known leaking of chemicals from our natural, petroleum-free
    bottle to the water inside. Primo single-serve bottles are also 100% BPA

  75. Ghede says:

    He is overreacting. It is simply the grocery shrink ray misfiring.

  76. doctor_cos wants you to remain calm says:

    @Dervish: “…the toxicity studies don’t hold much water.”
    Was that an intentional pun, seeing as how we’re discussing water bottles?

    And another wonderful use for corn! F*ck food prices, make fuel AND bottles out of corn instead of food.

  77. Ben Popken says:

    In a car in that heat for that many hours, I think you would be hard-pressed to find something that wouldn’t melt or shrink.

  78. Jay Slatkin says:

    @Ben Popken: What about normal plastic?