Science Experiment For Kids: How to Make Glowing Water

Looking for ways to pique your child’s interest in Science?  Let me tell you; hands-on experiments are the way to go!  There’s nothing like an erupting volcano or glowing water to really get their curiosity piqued.  Speaking of glowing water, here’s an easy way to make glowing water with just tonic water and a black light.

Pique Your Childs Interest In Science With This Experiment

Step 1: Pour tonic water into a clear container. Believe it or not, plain old tonic water glows under a black light — quite brightly, as well. To get this effect, start by pouring some tonic water into a container where you can see it. You can add it by itself or dilute it with water. However, the more water you add, the dimmer it will glow.

  • Tonic water is available at most local stores and supermarkets for just a few dollars. Be sure to get tonic water, not club soda or soda water. The bottle should say “with quinine” or something similar.

Pique Your Childs Interest in Science With This Experiment

Step 2: Shine a black light on the tonic water. All you need to do to get tonic water to glow bright is to illuminate it with a black light. Be sure to dim the lights in the room before you do this or it will be more difficult to see the glowing effect.

  • Black lights are available from specialty party stores (like Spencer’s, etc.) or online. The price for the black light often depends on its size and brightness — basic lights can cost as little as $20 or less.


Don’t worry about drinking the tonic water.  Making tonic water glow with a black light makes it look very strange, but it doesn’t make it poisonous, radioactive, or harmful to drink in any other way. However, tonic water is often high in calories and sugar, so enjoy it sparingly.

What’s Happening?

The Simple Explanation: The ultra violet (UV) light coming from your black light lamp excites things called phosphors. Tonic water and the dye from highlighter pens contain phosphors that turn UV light (light we can’t see) into visible light (light we can see). That’s why your water glows in the dark when you shine a black light on it.

Black lights are used in forensic science, artistic performances, photography, authentication of banknotes and antiques, and in many other areas.

The Detailed Explanation: Black light (also known as UV or ultra violet light) is a part of the electromagnetic spectrum. The electromagnetic spectrum also includes infrared, X-rays, visible light (what the human eye can see) and other types of electromagnetic radiation. A black light lamp such as the one you used emits a UV light that can illuminate objects and materials that contain phosphors. Phosphors are special substances that emit light (luminescence) when excited by radiation. Your water glowed under the black light because it contained phosphors. If you used a highlighter pen then the UV light reacted with phosphors in the dye. If you used tonic water then the UV light reacted with phosphors in a chemical used in tonic water called quinine.

There are different types of luminescence, they include fluorescence (used in this experiment, it glows only when the black light is on), phosphorescence (similar to fluorescence but with a glow that can last even after the black light is turned off), chemiluminescence (used to create glow sticks), bioluminescence (from living organisms) and many others.

For other fun and interesting Science experiments like this one that will most certainly fill your kid with an unquenchable thirst to know more, check out some of our other blog articles on Science here.  We’ve also got some of the most fascinating science kits on the face of this planet at


The instructional portion of this article was provided by wikihow, a wiki building the world’s largest, highest quality how-to manual. Please edit this article and find author credits at the original wikiHow article on How To Make Water Glow.  Content on wikiHow can be shared under a Creative Commons License.


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