Build Your Own In-Fridge Soda Fountain

Who doesn’t love an ice cold soda? Lots of people, probably. This one’s not for them. It’s for those of us that are tired of having to go through the arduous process of manually opening a bottle and pouring a drink. Wouldn’t it be cool if you could have your own soda fountain at home? [Kedar Nimbalkar] thought so, and built a soda fountain that you can install right inside a fridge.

The system is based around using small pumps marketed as “6V DC air pumps” on Amazon. [Kedar] uses an indirect method of pumping the soda in this project. It’s a sad fact that it’s hard to find a cheap pump that’s safe to use with fluids for human consumption, and on top of that, many types of pump out there aren’t self-priming. This means the pump needs to be charged with fluid to work, which can make changing empty bottles a real pain.

Instead of pumping the fluid directly, the pumps instead push air into the top of the sealed soda bottles, which forces soda out of another tube in the bottle. This means that the pumps themselves don’t have direct contact with the soda which is a great design when working with stuff you’re going to put in your body. Following on from this careful design, the tubing selected is food safe. Unfortunately, even though the pumps don’t directly touch the soda itself, it’s highly unlikely the pumps chosen (designed for aquariums) are genuinely food-safe themselves.

When you’re building a beer funnel setup for Australia Day/4th of July/Other, using all manner of industrial or agricultural fittings may be a relatively low risk, as it’s a one-off exposure. But if you’re building a system handling products for human ingestion that you’re using on a regular basis, you really do want to make sure that the parts you use aren’t slowly poisoning you. There’s many ways this can happen — parts may corrode or react with substances in the food, plastics may outgas, or there may be lubricants in the parts that have toxic compounds in them. Just look what can happen if you drink wine out of a gun barrel — and that was from a single exposure!

Overall it’s a cool project, and one that would be especially fun and educational to do with children. Young humans are well known for their predilection towards sugary beverages, and have minds ready to be filled with knowledge about pumps, safe food handling practices, and of course, electronics. We also like [Kedar]’s use of commonly available materials, like a plastic food container for the enclosure. The project would be a great starter on your way to building a more complicated cocktail-mixing barbot. Video after the break.

We know peristaltic pumps are the go-to for safe liquid pumping. Anyone know a hacker friendly way of pumping air while ensuring all parts of the system are food safe? The most creative solution we’ve seen is to use breast pumps but it wasn’t ideal. Let us know your own tricks in the comments!

93 thoughts on “Build Your Own In-Fridge Soda Fountain

    1. It’s amazing the people criticizing sugar water drinking don’t have any problem drinking it after they let bacteria process it into something even more toxic to your body.

          1. Again, you don’t drink nearly as much beer as you do soda, and beer contains about half the calories.

            And when you do, it becomes a problem just the same. Think about it.

          2. “and beer contains about half the calories.”

            Uh, no. Average of all brands gives 136 calories per 12 oz serving. 12 oz can of coke? 140. Beer and soda contain on average pretty much the exact same.

            “Again, you don’t drink nearly as much beer as you do soda”

            Yeah, uh, no. About 30% of the people in the US drink at least 1 soda/day. Over 40% of the people in the US drink at least 1 alcoholic drink a day, and the majority of that is beer. If it’s not OK to have a soda fountain for caloric reasons, it’s not OK to have a beer tap either.

    1. The stuff labelled “Fanta” in the USA is nothing like the real thing. Proper Fanta might still be sugar water, but at least it tastes of something.

      But I’m more confused by the “Beauty & Care” compartment in the fridge.

    2. Having sampled the natural orange juice colour fanta in Europe, that also has actual oranges in it, I too was shocked by the stomach churning dayglo orange colour available in North America and elsewhere.

      Also sunkist, if available is much the same. Very seldom seen though, think it’s named something like Orange C with sunkist, but yah, not sunkist.

    1. You can even see that this drinks are totally flat, no single bubble of CO2, the stuff looks like water in the video.
      FAIL!
      Of course CO2 pressure and valves would be the way to go. There is a reason it’s done like that in restaurants.

          1. The *lowest* prices I’ve seen usually put it near-equivalent to buying 12-packs of 12-oz cans and violently above buying individual 2-liter bottles. So unless you’ve got some huge driving desire to have a soda fountain, it doesn’t make sense. I always figured the prices those places charge individuals must be way marked up over restaurants.

    2. That’s what I was thinking – keep the drinks fizzy for longer (if you pump the CO2 through the liquid, it could even refresh the fizz) *and* provide a positive pressure to force the liquid out.
      Probably need to put a restriction of some sort to stop the high pressure of the CO2 cartridge giving you an instant shower with the drink as it gets pushed out!

    3. i think to do this for real you need a co2 tank, stainless steel water tank (that can be pressurized), refrigeration (figure the best way is to get one of those mini-fridges, though you can probibly build a unit that fits in any fridge), and an air compressor. thats just to make the carbonated water, you also need a fountain head which does the mixing between the carbonated water and the syrup. then any neccisary pumps, plumbing, fittings, valves, and sensors. stainless steel end to end should be pretty food safe. you just need to keep the co2 tank at a certain pressure under refridgeration and the water will just absorb the co2 under those conditions and become carbonated. i thought about building one but its out of my budget.

  1. The clear bin in the door says “BEAUTY & CARE”. Is this for makeup etc? I’m more used to bins in the top of fridge’s door saying “butter” or “dairy”.

  2. On the plus side, there’s no microcontroller, on the minus side, the list goes on.
    It’s demonstrates a useful principle that should have been applied to getting oil or diesel out of 25 litre drums, or something along those lines.

  3. OK, 1+ for the “hack” of using a pump to transport liquids.
    Then: 10- for having to leave the fridge door open all the time, wasting lots and lots of energy (to cool down the interior again after you close it), the risk of spoiling sugar water all over the place in there, providing perfect grounds for bacteriae and co …

    Sorry – not a “cool” hack at all.

    1. the ambient air in the fridge doesn’t have much heat capacity. the things in the fridge on the other hand do, and entropy is slow. its sort of like how going out into the rain is somehow going to give me a cold virus.

      1. Once you open the door, the outrush of air pulls in warm air from above, and creates a convective pump, fanning all your foodstuffs with it.

        Imagine sitting in front of a fan that puts out 40 C air – feels pretty hot pretty quickly. That’s the same temperature difference to room temperature as your room is to the inside of your fridge.

        1. You know, it’s really surprisingly contradictory how many different answers there are out there to this basic question. Lots of places say you lose a lot of heat (some places claim between 7-50% of the energy is used in a fridge by opening the door) whereas Michael Blasnik, who’s actually a energy efficiency expert published in the field, says that at most it’d be a tiny amount. Dwarfed in fact by putting something hot into the refrigerator.

        2. I can play this game. Imagine you place that same fan in front of a gallon of water that is uniformly 4 degrees C (upper temp range for a fridge). How long does it take to uniformly heat that gallon of water even 1 degree C? Probably longer than it takes to pump the soda in the video.

  4. I might think that a reasonable indicator that aquarium pumps are non-toxic is the fact that the fish are not swimming belly up (the differences in metabolism to humans notwithstanding)? Would I be wrong?

    1. My thought. :-) Most fish are generally quite sensitive. I would have more fear against microbes and mold growing in the tubes.

      But I would not like any system which keeps the drinks depressurized for any length of time. There is a reason that real soda and beer dispensers keep the beverage pressurized with CO2

      1. 5 liters per day?! You’re either not being honest, have an extreme metabolic rate or have your own zipcode because that alone exceeds a normal humans daily value of calories.

      2. Maybe you’re body is capable of producing a lot of insulin to push the sugar in the cells. Still not healthy, though. Sugar is damaging, whether it’s in the blood or in the cells.

        1. Robot detected!

          Seriously that’s bullshit – your brain consumes mainly glucose and glucose is the main energy source used for cellular respiration. Without sugar one will die, diabetes sufferers using insulin “have” to have some sugar on their person as emergency medication if the blood sugar level drops too low.

          Sugar can be damaging just like everything else, it’s the dose that makes the poison etc.

          1. “it’s the dose that makes the poison etc.” — The WHO recommends no more than 50 grams of sugar per day, and sees additional health benefits reducing that to 25 grams per day (less than 1 can of coke). 5 liters of cola contains 500 grams of sugar (more than a pound)

            “Without sugar one will die” — true, but you only need a little bit, and you don’t need it in your diet, because your liver and kidneys are perfectly capable of synthesising the necessary amount. And if you put it in your diet, it’s best to eat slowly digesting complex carbs, not sugar water. Your brain needs 150 gram glucose per day, not in the next 15 minutes.

          2. Glucose is one kind of sugar. Sugar in sodas is half glucose half fructose, and the latter half does a number on your liver as it requires the same enzymes that break down alcohol to convert to glucose. It basically gives you Cirrhosis over time.

            The point about diabetes is that sugar is high GI food, which means it raises your blood sugar levels higher and faster than anything else and gets stored as fat because the cells won’t have any immediate use for it. This leads to obesity, which leads to insulin resistance, which leads to diabetes.

            https://en.wikipedia.org/wiki/Insulin_resistance#Diet
            >High-carbohydrate, low-fat diets were found by many studies to result in elevated triglycerides,[30] in part due to higher production of VLDL from fructose and sucrose, and in part because increased carbohydrate intake tends to displace some omega-3 fatty acids from the diet.

            >Several recent authors have suggested that the intake of simple sugars, and particularly fructose, is also a factor that contributes to insulin resistance.[31][32] Fructose is metabolized by the liver into triglycerides, and, as mentioned above, tends to raise their levels in the blood stream.

          3. “The point about diabetes is that sugar is high GI food, which means it raises your blood sugar levels higher and faster than anything else and gets stored as fat because the cells won’t have any immediate use for it.”

            Absolutely right! But then, guess what happens when you don’t eat, you’re a bit hungry, and your body needs energy? It breaks that fat back down and gets the energy from it. The problem is that in modern society, when people get hungry, they eat, because food is nearly always available, and discipline in eating isn’t exactly stressed.

            The idea that sugar is evil poison is just flat nuts. Of course it isn’t. Is it dangerous in a society where self-control related to eating is virtually non-existent? Absolutely. But alcohol’s far more dangerous, and an article about someone building a beer tap would never result in flame threads about how you should never drink beer.

          4. “It breaks that fat back down and gets the energy from it. The problem is that in modern society, when people get hungry, they eat, because food is nearly always available, and discipline in eating isn’t exactly stressed.”

            The problem is that a high sugar diet makes the cells “lazy”. They don’t make enough enzymes to burn fat effectively, so after the fat is stored, and sugar is running low, the body signals the brain to eat some more sugar, instead of switching to the stored fat.

            If you switch to a low sugar diet, the cells improve their fat metabolism to a point where 90% of energy can be derived from fat, resulting in less hunger feelings and easier weight control.

          5. ” They don’t make enough enzymes to burn fat effectively, so after the fat is stored, and sugar is running low, the body signals the brain to eat some more sugar”

            Isn’t this exactly what I said? The solution doesn’t have to be eat less sugar. It can also be “ignore those signals.”

    1. Save your ire for something that makes sense. The US consumes roughly as many calories in beer as it does soda (given the age-21 restriction) and beer receives none of the criticism.

        1. No, but unless the 5 year olds are going to the store and buying the soda themselves, they’ve got an adult deciding whether or not they can drink it. So what exactly is the difference again?

      1. There’s plenty of criticism on drinking alcohol. Why do you think the age-21 restriction is there in the first place ? And it’s not only the calories. Sugar has nasty side effects that have nothing to do with calories.

        1. The criticism regarding beer/alcohol is *pathetic* compared to the recent outrage against soda. The age-21 restriction on alcohol is there because it can *kill children,* whereas I’m pretty damn sure that if an 8-year old guzzled an entire 12-pack of soda all they’d have is a stomach ache.

          10% of the people in the US drink the equivalent of *one hundred alcoholic drinks* per week. That is so ridiculously worse than the top percentage of soda drinkers that it’s not even funny. It causes the deaths of thousands of *other* – non-drinking – people a year.

          And yet in Philadelphia, soda is taxed well over an order of magnitude higher than alcohol.

          “Sugar has nasty side effects that have nothing to do with calories.”

          The basic problem with sugar-sweetened beverages is that it adds calories but doesn’t satiate. In other words, there’s a feedback mechanism – almost like you replace 100 calories of food with soda, and your appetite wants to add 100 more. So if it’s unchecked by the *person drinking it,* it can runaway. So wow, that sounds like a bad thing, right?

          Except I can use almost those exact same words with *alcohol* as well. So is alcohol evil and should be banned completely? No, of course not, because a person *with discipline* can drink alcohol and be fine. A person *with discipline* can drink soda and be absolutely fine. It’s just an appetite problem. You end up hungry. So what? Food tastes better when you’re hungry. Teach disciplined, balanced eating habits and paying attention to caloric intake and weight, and people will be fine.

          1. “I’m pretty damn sure that if an 8-year old guzzled an entire 12-pack of soda all they’d have is a stomach ache.”

            The rising number of young children with type 2 diabetes says otherwise.

          2. If you think an 8 year old guzzling an entire 12-pack of soda *one time* causes diabetes, you’re nuts. But an 8 year old chugging a bottle of vodka is dead.

            The problem isn’t soda, it’s the pattern of behavior that soda enables in people who don’t have the discipline to deal with it. Which is almost word-for-word what you’d say about alcohol.

  5. How about a little common sense?
    No, an aquarium air pump will (probably) not give you the nasties like drinking out of a gun barrel does. If it looks & smells clean, then it is good enough. Not for you?-> fine, don’t do it and go elsewhere. No need for foodsafety nazi’s.

    As for what gear to use: treat it like any other pressurized liquid dispenser, use some simple homebrew beer parts from china. If you do not leave it pressurized (no tap at the end of the line), it will go flat and/or leak out. For flat drinks, the open tube setup is refreshingly simple to operate and clean. However, it may siphon contamination from the pouring spout back into the container. No problem for smallish bottles that empty quickly, larger containers may become alcoholic or acidic over time, at which point the contents will leak out due to pressure build-up.

    1. Looks and Smells Clean ™ may work for ‘annemuls’ which generally have vastly better sensory equipment than us poor ‘huemuns’ but it simply isn’t good enough.

      The COSHH regulations exist for a very good reason.

  6. I would have tried to use a cheap Peristaltic pump (£20-30) like they use in drinks machines and such. Maybe even this was too expensive but the advantages outweigh the cost disadvantage.
    1. Easy to remove and replace the foodsafe silicon tubing.
    2. When the pump is stalled, the silicon tube is sealed.
    3. When used in conjunction with a one way valve for air displacement, the whole set-up is air tight, helping keep the fizz slightly longer.

      1. True and that’s the good thing about the peristaltic pumps, simplicity and easy to print but for <£30 I would prefer to buy something that is likely to be more reliable and already product tested so I can spend my time on other projects.
        I tend to use the 3D printer for custom things I cannot buy cheaply.
        I am also suspecting they didn't have access to a 3D printer.

      1. We can hit a 44 or 45C heat index/humidex with the humidity, but I still gag on anything fridge cold. When I need to download fluid I wanna guzzle a pint of it, not sit around sipping it like some Bogan with delusions of culture.

        1. admittedly the 2-5 deg range can be a little too cold but for most households the alternative can be drinks that are too warm.
          We keep still flavoured water drinks in the cool dark garage as its the coldest place in the house in the summer but grabbing one of them in the summer is still not as pleasant as a colder drink from the fridge.
          I have removed the bottom salad crisper drawer and fill the void with the drinks as its the warmest part of the cold fridge when I checked the temperature and everyone in the household prefers it from here than the garage in the summer.
          I must say I do prefer it from the garage though in the winter as its nice and cool but not too cold.
          I used to use a Husky drinks chiller which was fine as its warmer than a fridge but got fed up of it always icing up (being a hackaday reader, maybe I should have just made a defroster for the drain channel.;-)

    1. Why since the invention of refrigeration should anyone have to drink a beverage warmer than 7C on a summer afternoon?
      Seriously some stuff like beer and pop are undrinkable when warm and tea is only good hot during the winter in the summer I want it iced.

      1. Not ‘One Of Us’ then :)

        The English drink tea whenever it is appropriate and not at the whim of the external temperature.

        Mind you, we don’t have much option given the ‘variability’ of our weather…

  7. The most strict keto diets rely on ketogenisis making glucose from protein as the brain cannot run on only ketones like muscles can; but humans are (I believe)uniquely adapted to do that so all is good. The cool thing is that keto makes just enough glucose to fuel the brain and thus need not bother with dumping insulin to permit glucose fuel to enter the muscles which are burning ketones.

  8. So I am guessing where he is soda is not carbonated? because the way he has it designed, the bottles will self dispense without a high pressure valve closing off the whole system.

    1. Sure, if you wanna risk getting diabetes faster than using the real thing…
      http://www.nature.com/nature/journal/v514/n7521/full/nature13793.html

      Then there’s numerous doubts around Aspartame, sucralose gives you the shits, stevia tastes like you licked the sugar plum fairy’s crotch, xylitol is particularly effective at nuking all your symbiotic bacteria, cyclamate has a cencer association…

      I do believe that saccharine is actually one of the safest, but it doesn’t get in pop much. Also hard to find here as an additive sweetener.

      Also one should be skeptical about how artificial sweeteners are approved, usually as a diet supplement, something you’re meant to use for a few months as a crutch while you are reducing, not frequently and copiously through all of your natural life.

      1. Sadly, much of the cyclamate research has been discredited.

        The ‘scientists’ (there are other, more appropriate names for them) manipulated the parameters of the experiment – ten times the rate of cyclamates to sugar by weight, ~200-300% the manufacturers recommended maximum – and lied in their report to disguise the fact.

        1. Well if it’s done on the assumption that a “reasonable person” would have a couple of 250ml sodas a day, 500ml, then when you’ve got people talking of drinking 5 liters a day over decades then yah it seems like a milligram/years issue worth comparison with the lab rat study.

          I mean, rats, mice only live a couple or three years naturally, so overdosing to get some time compression for long term effect estimation is going to be a given.

          1. That wasn’t what happened in much of the early research into the long term effects of cyclamates. The ‘researchers’ deliberately set up their experimental protocols to achieve a predetermined result and got caught at it.

            BTW: 5 litres a day seems a bit excessive and unless they’ve got the bladder capacity of a horse…

      2. You shouldn’t read conspiracy websites – those DO rot your brain.

        Aspartame is considered very safe and the lies still spread about it are ludicrous. It is however very dangerous to people with a very rare condition.
        Sugar alcohols (which are neither sugar or alcohols) often do interfere with digestion, some more than others. Erythritol are generally tolerated well.
        Xylithol (sugar alcohol) have some repairing effects on teeth (how much is disputed) but doesn’t nuke anything.
        Cyclamate is also considered very safe. It is the most researched sweetener and (after culling obviously bad research) have no indication of being a danger.

        (Writing this while drinking a glass cola sweetened with a cyclamate – aspartame mix)

        1. heh… ‘Obviously Bad’ is certainly one way of describing the work in question. I believe the official report used the word ‘Fraudulent’, but that was thirty-something years ago and my memory isn’t quite what it was :)

  9. One small flaw all the soda will quickly go flat and there’s few things worse than getting flat soda.
    This might work for non carbonated drinks such a tea or juice.

  10. IMHO the problem with this air over water system is if the pump say uses oil, you will still wind up with oil in your your water. It will settle out of the air and it has no place else to go. If you want a truly isolated system you need to make a food safe rubber bladder that you can put in the fluid, and than pump whatever into the bladder to expand it. As long as the bladder does not rupture, and the stuff you have on both sides will not permeate it, you are good to go.

    If you want real soda or soda water your best bet is just to buy a carbonator. The tricky part with carbonating water is that you dissolve a lot more CO2 in cold water. Most commercial soda fountains use “cold plate” in the ice machines ice reserve to pre cool the water going into the carbonator. This would be tricky to pull off well at home without having a dedicated fridge/freezer for it. The cold plate wants to be just enough about freezing that is does not freeze up. The freezer in your fridge is too cold, the cold plate would freeze, and the fridge is too warm to work well.

    In my collection of things to do, I have an old refrigerated water fountain and a commercial carbonator. The plan is at some point in time to marry the two into a self contained on demand fizzy water tap.

  11. Having read all the above, the perfect drink would, contain no chemicals (because they kill you), be neither sparkling or still, be at the perfect temperature (2 to 90degrees c) and not be bright orange.
    that sounds simple, I can’t imagine why no one has produced it yet, in the meantime I’ll drink cider kept in a fridge and water kept in pipes and consume all the chemicals therein.
    I can’t help feeling that if you have the skills to dream this up and execute it so effectively, you could probably develop the skills to pour drinks from a bottle into a glass, but we all started hacking somwhere, and we all have embarrassing shit lurking in the bottom of a box that we can’t even scavenge for parts. (Because it’s that bad and we don’t want to even look at it)

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