Have you ever wondered how one of those perpetual Heron’s fountains works? You know, those ones with a seemingly infinite supply of water?

You could look it up on Google, but where’s the fun in that? Instead, why not have YouTuber DaveHax explain it with a miniature Heron’s fountain built out of bottles and straws?

YouTube video

The build itself is quite simple. Drill a couple of holes slightly larger in diameter than the straws into three bottle caps. Two of these caps should be glued together, allowing one bottle to stand upside down atop the other.

The upside-down bottle should have two drilled holes on its bottom (which is now its top). This will allow the straws to pass through to the fountain top. The Heron’s fountain top is made by cutting out the plastic top of the third bottle.

Heron's fountain

Getting the lengths of the straws is a bit tricky but with a little bit of color coding, anyone can get it right.

Two connected straws (denoted by their red color) should feed into the three bottles. A shorter combination of straws (yellow) should protrude just a few inches through the top of the bottom bottle. However, it should also cover most of the space inside the upside-down bottle. Finally, a set of blue straws should run down the length of the upside-down bottle and protrude slightly from the bottom of the Heron’s fountain top.

Got all that? No? Well then, here’s an image DaveHax made which better explains the straw placements:

Heron's fountain

As you can see, the Heron’s fountain works using water displacement and air pressure. When you fill up the fountain above, water flows down the red straw to the bottom bottle. The air inside the bottom bottle then gets pushed via the yellow straw into the upside-down bottle, which in turn pushes the water inside that one through the blue straw on top of the Heron’s fountain.

Heron's fountain

The Heron’s fountain will continue working until the water totally fills up the bottom bottle or goes below the blue straw in the upside-down bottle. Once that happens, all you need to do is flip the fountain upside down. This fills up the upside-down bottle, and whatever excess water remains should fall into the bottom bottle. You can then take this excess and use it to fill up the fountain top above; starting the process all over again.

In more sophisticated Heron’s fountains (i.e. the ones you see in malls and parks), an electronic mechanism pours more water into the fountain above. This eliminates the human element; bringing the world one step closer to machine domination.


Carlos wrestles gators, and by gators, we mean words. He also loves good design, good books, and good coffee.