glowing water experiment

This glowing water science experiment is both fun and easy to do.   Kids will learn about the properties of UV light when using a blacklight to try to make various cups of water glow. 

Supplies Needed

  • Glowing Spooky Soda  
  • Tonic water 
  • UV Blacklight
  • Bleach (optional) 
  • Clear plastic disposable cup 
  • Medicine Dropper 

Glowing Water with Florescent Paint 

  • Neon colored water-soluble or tempera based fluorescent paint. Lemon yellow and lime green glows the brightest. 
  • Glass of water in a disposable cup
  • Spoon
  • UV Blacklight   

Glowing Water with Highlighters 

  • Neon Highlighters that glow. (Check to see if the highlighter glows by writing on white paper and shining a black light on it). The color influences the intensity of the glow. Yellow highlighters may possibly glow the brightest
  • Scissors, pliers, or knife 
  • A Glass  of water in a disposable cup
  • Spoon
  • UV Blacklight   

Glowing Water with Glow Sticks 

  • Large glow sticks 
  • Scissors or knife 
  • Glass 
  • Water in a disposable cup
“Normal” Water
  • Water in the same disposable cup style as the others.

What Mystery Are We Solving?

Why does tonic water become spooky soda that glows in the dark when UV blacklight shines on it? Is it the same reason why waterlogged highlighters create glowing water or are the chemistry different?  

Safety Issues

DO NOT DRINK the spooky glowing water. Some of the ingredients are toxic, for example, the glow sticks and tonic water with bleach 

Adult supervision is recommended to limit the mess caused by highlighter ink or paint. Broken glow sticks may have pieces of glass inside that could accidentally cut fingers. Bleach may burn if it comes into contact with skin and could bleach colored clothing.  

How To/Directions

There are many ways to attack this expirment.  To begin, fill your normal water cup and set it aside. 

You can then choose whatever of the following “glowing” water sources you want – or all of them – to compare against normal tap water.

Glowing Water

  1. Turn the lights off and shine the black light on the bottle of tonic water. 
  2. Pour some tonic water in a glass. 
  3. Add a few drops of bleach and notice the difference when the ultraviolet light shines on it.  The spooky water isn’t spooky anymore. 
  4. Pour tonic water in another glass and dilute with water. Notice how the glowing effect decreases.   

Glowing Water with Florescent Paint 

  1. Fill glass three-quarters with warm water. 
  2. Add the paint to the glass of water. 
  3. Stir to dissolve the paint in the water. 
  4. Immediately turn off the lights and shine the black light on the glowing water. If you wait too long to perform this step, the paint will sink to the bottom of the glass spoiling the effect.  

Glowing Water with Highlighters 

  1. Pour a few inches of water in a glass.
  2. Use the pliers to remove the highlighter felt or cut it with a knife. Be careful the ink will drip.
  3. Immerse the felt in a glass of water. Be mindful that the more water the less the effect.
  4. Wait at least 10 minutes for the ink to be released into the water. 
  5. Remove the felt.
  6. Stir the water to distribute the color.
  7. Turn the light off in the room so that the room is dark.
  8. Switch on the UV light and observe the neon glowing water.  

Glowing Spooky Water with Glow Sticks 

  1. Fill a glass with water.
  2. Bend the glow stick to break the glass tube inside. 
  3. Cut off one end of the glow stick. Be careful of possible glass pieces.
  4. Place the plastic tube in a glass of water for a concentrated glowing effect at the bottom of the glass. Remove the capsule and pour the liquid in the glass of water for overall glowing water.
  5. Turn the lights off. You don’t need a black light to see the effect of the glowing spooky water.  


What Just Happened Here?

Blacklight releases invisible UVA radiation (ultraviolet radiation type A) that is harmless. The purple light you seen with a black UVA light, however, isn’t the invisible UVA radiation 

The chemical phosphor absorbs the invisible UVA radiation and releases a visible light which is seen as glowing in the dark. In the highlighters, paint and sticks the phosphorus is fluorescent which releases the light quickly and doesn’t last long.  

The fluoresces effect in tonic water, however, isn’t because of phosphorus. Tonic water contains the chemical quinine that gives the tonic water the bitter taste. The quinine is excited by the blacklight and it absorbs the UVA radiation. When it returns to its normal unexcited state, it releases the visible blue glowing light 

The chemical bleach is an oxidising agent that prevents quinine from absorbing the UVA radiation. The oxidising agent breaks the chemical carbon-carbon double bonds and the spooky water stops glowing bright blue.

One Comment

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.