Glowing water is useful for making spectacular fountains, “magic” potions, and for added pizazz for a party or science project.
Chemicals to Make Water Glow in the Dark
Ordinarily, water doesn’t glow. There’s actually an exception to this. Water in a nuclear reactor does glow blue due to Cherenkov radiation. So, if you’ve got some spent nuclear fuel rods sitting around the house, the easiest way to make water glow is to toss one in.
Assuming that’s either impractical for you or else you fear radiation poisoning, you can use chemicals to make water fluoresce under black light or else phosphoresce (truly glow in the dark). Here are chemicals you can add and what to expect:
Tonic Water: If blue is your color, save yourself a lot of time and effort and simply use tonic water with a black (ultraviolet) light. Tonic water contains quinine, which glows bright bluel Tonic water is safe to drink.
Vitamin B12: Adding vitamin B12 adds a bright yellow glow under a black light. Vitamin B12 is usually sold in tablets that don’t dissolve well in water. To get the vitamin away from the powdery filler, dissolve the tablet in a small amount of vinegar. Run the mixture through a coffee filter to remove particulates and add the liquid to water. Vitamin B12 is safe to add to drinks.
Chlorophyll: While chlorophyll is green, it glows a dull red under a black light. If you add it to water, it tends to sink to the bottom of a container, illuminating it from below. Chlorophyll is safe to put in drinks, but it may add a “green” flavor, depending on your source.
Highlighter Ink: If you want a rainbow of colors, add ink from highlighter pens to water and use a black light. First, check the highlighter ink under UV light, because not all of them are actually fluorescent. Yellow and green are pretty reliable. Orange and red are iffy. Blue and purple rarely glow under black light. To get the ink from the pen, carefully cut the pen open (I used a knife and a cutting board) and use pliers or tweezers to extract the ink pad from the pen innards. Soak the felt in a small amount of water. You can store this “glow ink” in a plastic bag for future use. Highlighter ink is non-toxic, but isn’t meant to be ingested and tastes awful. Use it as a decoration, but do not add it to food or drinks.
Glow Powder: Make true glowing water by either adding phosphorescent glow powder to the water or placing it below a clear container holding the water. Some glow powder is deactivated by water, plus it doesn’t dissolve. Since the powder sinks, you’re better off illuminating the liquid from below by adding “glow” to its container. Remember to charge the powder with a strong light source (ideally the Sun or a black light) before turning out the lights. A good powder keeps glowing a full day.
As a side note, if you don’t like either nuclear or chemical methods of making water glow, you could add a bioluminescent organism to the water. Dinoflagellates produce glowing blue tides. You can buy these creatures online or visit the ocean to see them in their natural habitat.
Glowing Water Video Tutorial
If you’re unsure how to go about dissecting a highlighter, here’s my original video that shows how to do it and what to expect when you turn on a black light.