Converting A Bottle Style Water Cooler To Self-fill From The Tap


[Roy Bean] thought it was pretty silly for the Milwaukee Makerspace to keep buying bottles of water for their water cooler. He rigged up a system that automatically fills the refrigerated reservoir in their water cooler. It’s a functional hack that also provided an excuse for him to learn about a couple of different sensors.

What you see above is the meat and potatoes of the hack. The well is where water from a bottle drains into the cooler. This has been covered with a sheet of acrylic to keep the drinking water clean. There is a copper pipe which has been plumbed into the tap water supply. The other two bits are redundant level sensors to make sure the water valve shuts off without overflowing. One of them is a capacitive proximity sensor, the other is a conductivity sensor hacked together using stainless steel hardware submerged in the pool.

If you’re worried about the taste or odor of your tap water just add in a single or multiple stage under-counter filter system when plumbing in the water line. The filters are easy to find and we’d bet they cost less than a contract with a bottled water company.

[Thanks Pete]

70 thoughts on “Converting A Bottle Style Water Cooler To Self-fill From The Tap

    1. h2o solenoid valves fail all the time. I service ice machines and they fail with blow-by primarily due to chlorine attacking rubber seals and diaphragms. This causes overfilling of the units and loads of water going down the drain. Moral of the story: either rebuild valves as a precaution every 2 years, provide an overflow drain tube and keep it clear of algae, or in this case just use a float valve with a strainer upstream of it (which has a failure mode of clogging up not blowing by).

  1. I can understand finding a project to try out sensors on but why does everyone skip the easy route of using a simple float switch? Contact sensors are prone to failure due to the fact water will leave deposits on the probe(s).

    Typically, in industrial applications we use sensors to calculate volume, not for simple fill it up until here type applications.

    A way to resolve the valve failure situation that [peter] brings up would be to first start with normally closed solenoid, if you’re paranoid then use two in series. If you want an alarm then use a flow switch and check for flow when the valve(s) is closed.

    1. I think the capacitive proximity switch is actually more reliable than a regular float switch, those things are made to control very expensive industrial processes and do not fail easily. They are usually hermetically sealed so they won’t be damaged by moisture either.

      I would have probably skipped the conductive sensor completely and gone with two capacitive or one capacitive and one single pivot arm float switch, and as you mentioned dual NC solenoids.

      1. Actually… no. The capacitive prox switches are easy to fake out with a little water on the sensor. Floats tend to be more reliable and less prone to false positives and fast edges from ripples. Now I’ve seen good results with tuning fork style level sensors, but those tend to be pricy. I also have a 2m $6000 guided radar sensor sitting under my desk, but that was a victim of Hurricane Sandy.

        1. I haven’t had that problem with the cap sensors, if you set the sensitivity down a bit you need much more than some stray water on the surface of the sensor.

          The float itself may be reliable, but the switches aren’t always moisture resistant enough.

          1. Why does everyone skip the easy route of using a ball-cock? It’s the same kind of valve as in a toilet cistern, and if the power fails it still works!

          2. There are many solenoids that all you have to do is stick a magnet to the stem to activate them. On the other hand, why design such a robust water dispensing system without redundant power?

          3. While I think this project is just fine, I agree with Andrew. If it is good enough to keep hundreds of millions of magic poop stealing water chairs working for decades with no maintenance, it is good enough for most use cases.

          4. I have come across maybe a hundred leaking toilets in my year, toilets where the shutoff valve won’t close and water spills out the spillway of the cistern, So far i have never come across a leaking solenoid valve. (not saying solenoid valves can’t leak, just saying that purely mechanical valves can leak, and this setup has no drain to take the overflow)

          5. I would agree with Andrew about using a ball-cock, an incredibly simple solution that works in a no-power situation. But then to add to the nature of using a more technical solution, using sensors to determine if there is overfill and shutting off the valve in case the ball-cock fails and then sending an alert (email or SMS) and possibly a rotating red light!

      2. The conductive sensor is the most reliable sensor possible in this case. I would never dare to trust the capacive sensor to shut of the valve in time. Not in my house, not in my office! This must go wrong!!! (I have 30+ yrs of experience in industrial control)
        Conductive is in these case normally done with three probes and anything like a Omron 61FGP.

    2. Want even easier? a float valve. All done. or if you MUST have an arduino on it. a float switch at a lower limit and then just a timer to fill. It fills at a known rate, so a simple timer will work perfect every time. Add a high level emergency power off float switch for when you have electronics failures.

  2. I know a big part of the answer to “why?” is always just “because!” And that’s perfectly reasonable, of course.

    But, seriously. I’ve always found that the tap works just fine for dispensing tap water.

    1. We don’t have a tap in a convenient location at Milwaukee Makerspace. The bathrooms are on the other side of the building (and really, we don’t want to have to go into the bathroom just to get drinking water.) There’s a slop sink, but again, not really friendly to cups and drinking. The water cooler is located near the fridges, Kegerator, and “snack area”. (Yes, “snack area” because we are not allowed to have a kitchen.)

  3. The point of the water cooler is to serve purified water, so filling it with tap water is kind of gross to me. But nevertheless, it is a worthy hack. Nothing keeping this from being fed from an under-sink RO system just the same!

    1. Bottled water IS tap water. Sometimes they filter it, sometimes they don’t. It’s almost never “purified” (distilled), unless specifically labeled that way.

      1. Purified water is run through filters, distilled means it’s boiled-off and re-consolidated back into water. Different processes but with the same result about, I only learned about this recently when staring a 2 jugs from the same place, same size, same price, and wanted to know wtf the difference actually was!

        1. Some bottled waters, like Dasani and Aquafina, are simply filtered tap water from the municipal supply in whichever city the factory is located. (Which makes sense since those are Coca-Cola and PepsiCo products, and they need processed water by the lake-full.) These are usually labeled “purified water”, or something to that effect.

          Some companies (like Nestle) start with groundwater instead of tap water, but it goes through the same kind of filtration processes and ends up pretty much the same as filtered municipal water.

          The whole industry isn’t regulated as well as it could be, and the definitions can be vague at best. Personally I don’t like bottled water. It tastes like absolutely nothing and it costs a couple hundred times more than tap water (so the cost of an aluminum bottle and filtration pitcher can be recouped pretty quickly).

      2. In Arizona we have brick and mortar “water stores” which have rather impressive filtering systems. Depending on your water vendor of choice, you can absolutely know what you’re buying. Of course all the water is from a municipal source, but there are varying degrees of filtering (RO, carbon, UV, etc) and treatment it can also have to purify it. Please don’t cover the business if clean water with a blanket statement, it’s not right.

        1. How is that better than what comes out of your taps? I can understand you might happen to be thirsty and not near a tap, but that’s the only use I can think of.

          In the UK, at least, if it says “natural mineral water” then it’s regulated and has to come from a natural spring somewhere, and be tested. Anything else can be tap water. Even if it’s (and often is) labelled “spring water”. Presumably they bottle it in April, or it’s particularly bouncy.

          Dasani failed to launch in the UK when a few newspapers pointed out it was Manchester tap water. So’s plenty of other cheap brands of bottled water, but they don’t usually charge Coca Cola prices.

          1. Dasani isn’t just “tap water” and tap water is not filtered in any way. Dasani starts with tap water and then they filter it through a reverse osmosis membrane.

            Regular old city water has whatever is in your nearest river or lake, meaning if there’s another city upstream of yours that has a sewer system, then all the medicines people take in that city gets urinated into toilets and flushed into your drinking water. All the oils and chemicals on the roadways and sidewalks also runs off into that river when ever it rains.

            Tap water is processed this way: A pipe out in the middle of the river draws water into settling ponds where dissolved solids are allowed time to settle out of the water. Then they add chlorine to kill germs, and pump it to you. They do not filter it, they do not remove the chemicals, agricultural run-off, or anything else.

        1. Nah, the pipes are full of nothing but clean water. The pressure’s enough to ensure any leaks only flow outward, so nothing gets in.

          Occasionally, once per few decades, a town’s filtration might break down and they issue warnings and give out bottled water. Apart from that, what can go wrong? Most of the lead pipes are plastic now.

      1. Tap water is not filtered. I repeat NOT filtered.

        Tap water is piped from a river or a reservoir into settling ponds that allow the dissolved solids to settle out to reduce turbidity, then they add chlorine to kill germs and possibly fluoride to strengthen children’s baby teeth, and pump it to your home.

        There is no filtration. None whatsoever. They let solids settle out, add chlorine and pump it to you. The chlorine is why people don’t get dysentery from municipal water.

        However, if your water is sourced from a river and there is a city upstream of your city, whatever comes out of their sewage system and is pumped into the river ends up in your water. There is no mechanism in use to remove those pharmaceuticals, industrial and agricultural runoff, etc. Researchers at the City University of London often test the tap water and the water in the Thames river to statistically determine how many people are using cocaine and other recreational drugs, because they can detect the traces that are excreted in the urine of people using those drugs.

      1. No it is not “straight from a tap.” It might be sourced from a tap, but they filter the water through Reverse Osmosis and sometimes even using distillation.

        Tap water is just river water with chlorine. Seriously, read up a little bit on this subject, educate yourself. Tap water won’t make you immediately sick, but there’s all kinds of stuff in your tap water. My local water company sends out a quality report each year. There’s all kinds of stuff in your water. Perchlorates, Trihalomethanes, Arsenic, Cadmium, any pharmaceuticals excreted by people upstream of your water source, and so on,

    2. Especially since Milwaukee had an incident in its recent past where the tap water (drawn from Lake Michigan) was contaminated with sewage (dumped into Lake Michigan) causing the death of a child and numerous other people struck ill.

        1. 20 years is not very long on some accounts.
          20 years is way to long on other accounts.

          There was a time when the great lakes could not sustain life due to pollution.
          That problem prompted multiple regulations to clean up the lakes which allowed the fishing industry to return.

          Over the last few years, I have heard business persons complain about the “excessive” regulations that increase the cost of doing business in Michigan.
          The biggest problem with those complaints is that they tend to be directed
          towards the environmental regulations that safe guard the great lakes as well
          as the other environmental concerns that must be protected in order animals
          as well as humans to have sustained healthy lives.

          Whether 20 years is to long or not long enough depends on the selfish greed
          and lack of compassion on the part of the individual whose agenda is interfered

  4. the vertical floats used in toilet cisterns are excellent for this sort of thing. Add a hose coupling and right angle bracket to mount it on… it will even work in a zombie apocalypse when there is no power… rule #2 The double tap…

  5. I would be concerned that the conductive sensor would oxidise. Putting two electrized rods in water will electrolyze it (even if very slowly) and potentially produce nasty chemicals, and damage the sensor itself.

    1. You could solve that by using AC, or just periodically reversing the current. He’s using stainless steel. Isn’t that good enough? If he was really bothered I suppose he could use something gold-plated.

  6. I have a Automatic water change system on all my aquariums and I use three float switches. The one at the top of the tank is a overfull emergency stop. The next one down is the full level and the last one is the stop level for removing water.
    I have had this system in place for almost 2 years with no failures or even a E stop activation that wasn’t cause by me testing the switch.
    and I have another three switches in the water conditioner tank that also have never failed.
    I am always worried that a small snail or alga build up would keep the switch from working but so far no problems. and the e-stop switch is dry so I really don’t have to worry about that kind of failure on that switch.

    if any of the e stop switches gets tripped it kills the power on the pump and closes all solenoid valves.

    I am all for the KISS ideology.

    1. “I am all for the KISS ideology.”

      “I-I want to Rock and Roll all night, and party every day!”
      “I was made for loving you baby, you were made for loving me!”

      1. Only the high end ones have a chiller, and that one does not look like it has one, no chiller plate in the bottom of the resivoir… In true hacker style modify a cube fridge to hold a large coil of stainless line, then you can have never ending chilled water.

        A better choice is to just find and buy a broken post mix pop machine, then you get a chiller, carbonator and can even have sodas if desired. Broken ones are cheap and not hard for a hackerspace to repair to be better than new.

        1. One would imagine it does have a chiller. Or else the only useful bit of the dispenser would be the tap. Also the several mentions of “water cooler” in the description above kinda suggest it.

    1. Radio journalist Charles Kuralt once covered a story in an African village. He and other foreign journalists noted they had come down with “Montezuma’s Revenge” even though they’d been drinking bottled water the whole time they were there. One morning he found a boy who worked at their hotel refilling the water bottles at the village well. When asked why he was doing that, the boy replied, “Europeans like to drink their water from bottles”.

      1. That’s pretty funny. Obviously “only drink bottled water” is the wrong advice since simply being in a bottle doesn’t mean the water is clean. If the advisories were phrased differently (such as “only drink water that is known to be clean and free of pathogens” or something like that) then the journalists might’ve caught the mistake by noticing they were being given unsealed water bottles (so avoid ice and make sure EVERY new bottle is still factory-sealed, and make sure no water from melted ice is still on them if they were stored in a cooler).

  7. fartface: if you read the first sentence; “[Roy Bean] thought it was pretty silly for the Milwaukee Makerspace to keep buying bottles of water for their water cooler.”

    you’ll probably notice the words “water cooler”. The water is probably not cool enough out of the tap, thus the need for the water cooler.

  8. Many of the comments posted make sense IF Roy wanted to do things the simple way.
    But it seems that what is being missed is part of the whole point of this project, which is the opportunity to LEARN something about different sensors and circuts to drive them.

  9. I never understood why the tap water in the US is so bad. Here we get clean, odorless, tasteless water straight from the tap. Dont get me wrong, i really love america but sometimes it looks like a 3rd world country…

    1. “Pollution, pollution, they’ve got smog, and sewage, and mud!
      Just turn on your tap, and get hot and cold running crud!”
      -Tom Lerher “Pollution” from the album “That was the year that was” 1965

    2. Where is ‘here’? Tap water in the US is just fine, and for the most part pretty tasty. Milwaukee especially has a very good water supply. Any conclusions you’re drawing from way too many people drinking bottled water are misguided. It’s, for the most part, just smug.

    3. American tap water has chlorine to keep the water clean and germ free as well as fluoride to keep the bones and teeth strong. The anti-tap water crowd deem these things to be bad for ones health and therefore choose to not drink it. What they do instead is purchase bottled water which in most cases came from the tap.

      It would be more intelligent as well as sincere if they purchased a filtering system filtered the water coming directly out of the tap.

      1. But that costs more up front than buying a case of bottled water every week, and unfortunately many people tend to only look at short-term savings even if it costs more in the long term.

  10. This looks like an illegal installation, in that there is NO backflow protection. There is a required air-gap needed between the point of overflow and the opening of the incoming water supply line. Neat idea though……..

  11. I don’t get this at all. If you’re just drinking water from the tap, then why bother plumbing it over to a separate dispenser at all? Why not just go get your water…from the tap? The same “must add filters for cleaner water” argument applies to either way.

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