I originally made this project for the MAKE blog. It's a fun experiment that led to a lot of discussions about perpetual motion and free energy. My version does not exhibit either of these properties, but you may be able to fool people into thinking it does.

This is a really easy build and would be a perfect project for to build with your kids. Maybe you could even sneak in a lesson on fluid dynamics or perpetual motion?

Step 1: What You need: Supplies

Here is a lit of the items you need for the build. As you can see, it's not a lot. The total cost of build = $2 (you can scavenge the 3 water bottles)

(3) 16.9 FL OZ Water bottles
(1) 9" length of tubing
(1) 11" length of tubing
(1) 15" length of tubing
Small amount of clay

Note: The tubing is for aquariums and is 3/16" thin wall rigid tubing. Almost any tubing would work, even flexible, but the rigid makes it really easy. I was able to pick some up at a local pet supply store for about $0.50 per foot.
Oh, and also, thanks for the instructable, I had been looking for one of these a few years ago, but couldn't find any cheap designs that didn't use lab-type equipment. Good job, I think I'll build one.
Thanks! Send me pics if you build your own!
Unil the middle bottle is emptiedish. Basically, it's powered by water going from the middle to bottom bottle, and once the pressure it too low, it stops.
I'm making this for my mom thanks ; D
How long will it last?
Thanks for voting! I appreciate it.
I wonder if would an EXTREMELY large version of this (with a generator) would produce enough energy to add and remove water to keep it running forever.. and possibly generate enough power to run a house or charge an iPod or something ?
if you used the water to run a generator, then yes you would get electrical energy. the problem is, you arnt going to make more energy than is used up adding the water back into the system. the system can be as complex as you need, but with our laws of physics, it is impossible to produce more energy than used. this includes using temperature change, gravity and all forces that arnt part of the actual system as well.
Yes, a larger version would produce a larger amount of energy, maybe even enough to harness. However, the energy will eventually be used up. Unfortunately perpetual motion and/or free energy it is not going to happen with this fountain. Sad, but true.
Perpetual motion doesn't exist. There are many devices that utilize energy with amazing efficiency (perpetual motion clocks can power themselves for two days with a change in temperature of only 1 degree)<br /> <br /> But perpetual motion defies the laws of physics.<br /> <br /> However, I&nbsp;thought this was pretty neat.<br />
actually just because it defies our laws of physics doesnt mean its not possible, that sounds impossible to most but try to explain black holes while staying in the lymits of our laws of physics, i would explain some of this more scientificly but iv been stripping paint on 2 guitars all day as well as repainting several and to put it simply the fumes got to my head
No, perpetual motion is physically impossible.
really, huh? then what is powering all these spinning atoms that make the entirety of the thing we call physical reality? is it mass delusion? everything that exist is perpetually moving.. we are being hurled through space and even that space is being hurled through larger space and everything is constantly spinning..large and small. all of it. moving - perpetually.. someones gotta to say it.
That isn't what perpetual motion means.
Add a small turbine that can turn whatever water flow there is into electrical flow. This electrical flow can run a small compressor which will add pressure and keep it going forever :)
Can't believe I didn't realize this until after I&nbsp;posted.<br /> <br /> We didn't consider the waters' evaporation from the unit. Eliminate that and it'll last muuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuch longer.<br /> <br /> Maybe seal the top or something?
&nbsp;Nope, won't help. It's all powered from the pressure in the 2nd bottle. Once that pressure (generated from the gravitational forces on the water) is gone, the shows over. :)
After the water goes into the bottom container, and the air in the second, how does it reset, or is that the point where it stops?<br />
I wonder if u could make one that runs forever? (>_<)
That would be awesome.....but it isn't going to happen. Perpetual motion/free energy it is not. Eventually the pressure runs out and the water stops flowing. Although, it does last a surprisingly long time.
water stops running because its viscosiy, if you managed to do that same fountain with liquid air, as it has 0 viscosity, you could make it running forever
Wow, neat!
Hey that is so cool! What if there was a way to drain the lower container without disrupting the system, and use rain water to refill container b (the middle one). Then it could run forever, as long as it rains. I forget the name, but it's this cool little trick cup that when you start drinking out of it, it drains out the bottom onto the lap of the victim. It usually has a structure extending out of the middle of the bottom of the cup (on the inside). Once the top of the structure is exposed to air (after some drinking) little holes at its base let the fluid flow out. I wish I could remember the name of it so I could find out how it works. So basically, something like it would drain at a certain point when the water got to high.
You should make a giant one that is powered by rain.
That's a great idea! I have been thinking of a rain collection system, why not make it fun too!
<strong>I'm doing this right away! (rated 5 stars***** and favorited!)</strong><br/>
That's great! Please take some pics or a video and post them up online. Oh, and send me a link. I would really appreciate it!!!!
good job! it is quite interesting, considering how simplistic it is. 5*
Thanks. It was a lot of fun to make. Hopefully you you will try it too. It's strange to see it in person. It seems as though it shouldn't work, but I can assure you it does!
It is interesting, green, and classy good job.
Oh and I subscribed, hope to see more of this stuff from you!
I will be making more instructables in the future. Thanks for subscribing.
:) Just a note Html doesn't work on here.
Oooops! Thanks! I fixed it.
I agree, you got this thing made! Genius idea! Lol I feel like I finally understand physics.
Thanks! The real credit goes to Heron! Although he didn't use plastic bottles! ;)
Enjoy your new voltiac backpack! You have this contest by the NECK...
Thanks for you vote of confidence. There are a lot of great entries, and I am sure a lot more to come.
Lol, I was actually considering copying your article from make and just making it into an instructable, but you did this which is good also ;) 5 stars!
Haha, beat ya! Well, hopefully you make one anyway. If you do, send me a link. I love to see reader projects! Thanks!!!
How about using 2 litter or 3 litter bottles? How long do you think it will last?
Apparently from what I read, the larger the bottle, the longer it lasts.....as long as you don't increase the diameter if the tubing. I want to try and make one from 5 gallon buckets, I think it could last 1/2 hour or more.
never heard of it, but pretty cool
Thanks, I'm glad you like it.
Very nice. I have always wondered how these worked.
Thanks. They are a lot of fun. To be honest, I was amazed it worked, it just seems wrong. I was equally amazed at how long it lasted. If you make one for yourself, send me a link...I would love to see it. Thanks!!!
I shall try to make one and upload a few pics but I'm not making any promises.
Great! I hope you do!

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Bio: I make things.
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