Add water to a pitcher. Use pliers to pull the tip of the highlighter out and drop it into the pitcher of water. Use the pliers to remove the cap off the end of the highlighter and tap out the ink felt and drop that into your pitcher. Allow to steep for about 15-20 minutes. It doesn't take much time for the highlighter ink to color the water. Divvy up the water into your labware and repeat as needed. The highlighter ink can be used many times to make more glowing water. Feel free to use any color highlighter desired.