Siphon Chain Reaction




About: I made a book with some new projects in it! It's called Marvelous Makeable Monsters. Check it out here: The Oakland Toy Lab is a community-based wonder lab for students to build, ti...

Sometimes science sucks. But with siphons, that's actually a good thing.

Fill up your glass, and watch as it drains out from one to the next to the next. The siphon chain reaction is a sculpture in motion that plays on some seemingly simple and yet complex fluid dynamics. If you want something that looks purdy, this project is great. And if you want to wander down the rabbit hole of the debated science of how siphons work, this works for that, too. Let's siphon!

  • What: Siphon Chain Reaction
  • Where: In that cup, now in that cup, and now in that one...
  • Concepts: fluids, gravity, cohesion, siphon action, pressure
  • Time: ~ 1 hour to make
  • Cost: ~ $3 (mostly for the wood base)
  • Materials:
    • 3 cups (clear plastic)
    • 3 flexi-straws
    • Wood for base and upright (boards as you choose)
    • Wood for shelves (1x1s work)
    • Wood for platforms (paint mixing sticks work great)
    • Screws
    • Water and coloring
  • Tools:
    • Hot glue gun and hot glue
    • Scissors
    • Drill
    • Saw

Here we go!

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Step 1: Prep the Cups

First up is some pool maintenance.

Start with a clear plastic cup. Make a small hole in the bottom of the cup, and then widen it to the approximate diameter of your straws. You can use a pair of scissors, an X-acto blade, or many other cutting tools. Just be careful with those fingers! Repeat this for two more cups, and you'll have a lovely set of three.

I chose to cut my cups down a bit, too, so that I could fit them all closer together. The size of the cup is completely up to the maker, so feel free to vary!

Step 2: Insert Straws

And now for the miracles of flexi-straws!

Insert your straws so that the head of your flexi-straws are inside the cup. Scoot them down so that the end of the straw is as close to the bottom of the cup as possible. If you're having a hard time getting the straws through the hole you made, you can always use the straw folding method (in the second photo) to fit it through.

You may find you have a perfect snug fit, but in most cases touch up with some hot glue to make sure you have a good water-tight seal.

Step 3: Making a Stand

Time to prop these up!

Cut the bottom of the siphons off if you want to save a little vertical space, and measure out a piece of wood that can fit all three. Cut it to a size that works for you. Mark where you want to put each cup, so that they can flow from one into the other.

The stand can truly be hover you like, so feel free to venture in a different direction. The other steps are simply how I chose to do it.

Step 4: Create Siphon Shelves

Each of your cups needs somewhere to rest, so cut three platforms for them. I used 1x1s, but any scrap you have is fine. I measured them out so they'd be spaced evenly, and then drilled them in from behind to hide the screws.

Step 5: Build That Base

Every good stand needs a good foundation. Cut a piece of wood, and attach your vertical piece of wood however you see fit. I cut more 1x1 to act as braces and screwed it all together. You can use L-brackets or any other method you wish, so be feel free to be creative!

Step 6: Making Platforms

Our cups need to be supported, but there also needs to be space for the straws to drop down below. I grabbed a handful of stirring sticks, cut them down, and simply hot glued them on the shelves to make platforms for the siphons.

Again, feel free to alter the designs here to your liking!

Step 7: Siph-On and Siph-Off!

It's time for the magic to begin.

Place your siphons in a stack with a collection cup at the bottom. Color some water and pour it in the top siphon. You'll find that nothing drains out until the level reaches over the loop of the straw. From there pour in a little extra water and watch as your chain reaction comes to life.

One siphon drains all the way, then the next starts, the next starts, and as they start in a chain reaction, they finish as one, too with an interesting pattern of air pockets and liquid striping the straw.

A couple of options and explorations include:

  1. Take the siphon cups off and see if you can "juggle" water from one cup to the next.
  2. What drains faster, a siphon with a long straw end or a short one?
  3. If you fill your cup to just below the straw's elbow, is there a way you can "jumpstart" your siphon?
  4. What happens if you put oil and water in a siphon at the same time? (besides a mess)

Have fun, and as always, keep exploring. :)

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    9 Discussions


    2 years ago

    This is a cool idea. It was called a tantalus cup attributed to Pythagorus (I didn't know that, just found out when I checked for the correct spelling for tantalus). I vaguely recall seeing it used as a timing mechanism for a sprouting cabinet designed to produce large amounts of sprouts for chickens. Water would drip into the top vessel at a rate such that the siphon would empty X hours apart. As an aside, the water was collected and used to water the chickens as it was thought to have large concentrations of water soluble vitamins. Could use similar idea for hydroponics adjusting drip rate as indicated with a float switch in the catchment vessel. Sounds like your kids are lucky to have you as a teacher. Good instructable, thanks.


    3 years ago

    Thanks for presenting this. I made my version over the weekend, using a piece of pegboard as the back and some 2-prong 4" pegboard hooks to hold the cups. I then added a small pump with a switch to pump the water from the bottom cup back up to the top cup. I think this will eventually become part of a booth display for the Omaha Maker Group, probably with an Arduino and some sort of water-level meter in the bottom cup to control the pump. Thanks for the inspiration!

    2 replies

    Reply 3 years ago

    awesome idea! what size was that Pegboard? Do you have any issues with it it leaning or do the feet keep it in place?


    Reply 3 years ago

    The pegboard is standard 1/4" holes on 1" centers. I think the piece here started life as a 24" x 48" piece from the big box store, but I cut a piece off the end for another project, so the finished size is 24" x around 36".

    The feet (actually 10" long peg hooks inserted upside down on both the front and back) keep it from falling, although there is a little "springyness" to the whole assembly. It can bounce a little, but it won't fall over.


    3 years ago

    A couple of photos. Thanks again for an inspiring project!

    16, 9:20 AM.jpg16, 9:20 AM.jpg

    3 years ago

    great make, this would look awesome with dozens of beakers in one long row


    3 years ago

    great make, this would look awesome with dozens of beakers in one long row