A water-filled plastic bottle with pinholes does not leak when the lid is on, but when the lid is removed, water streams out. The effect is due to air pressure balancing the forces acting on the water inside the bottle.

1. Take an empty plastic bottle with a screw-on lid.
2. With the lid tightly on, use a pin to make a line of small holes around the side of the bottle.
3. Cover the holes with a strip of sticky tape.
4. Remove the lid, fill the bottle to the top with water, and replace the lid securely.
5. Gently peel off the sticky tape while keeping the lid on. Notice that water does not leak out.
6. Hand the bottle to a friend and ask them to unscrew the lid. Watch as streams of water squirt out of the holes.

Water Bottle With Holes Experiment - Playing With Rain:

Water Bottle Prank - Taras Kul:

📄 DIY Science: Water Bottle Pinhole Prank - National Science Week: https://www.scienceweek.net.au/diy-science-water-bottle-pinhole-prank/

• Try bottles of different shapes or sizes.
• Make fewer or more holes and compare the results.
• Test with warm water versus cold water to see if surface tension makes any difference.
• Perform the experiment outdoors with food coloring in the water for a dramatic effect.

• Perform over a sink, outdoors, or in an easy-to-clean area to avoid spills.
• Use caution with pins—handle them safely and store them out of reach of children.
• Do not squeeze the bottle, as this may cause water to squirt unexpectedly.

• Why doesn’t water leak out when the lid is on? (Air pressure outside the bottle pushes on the holes, balancing the force of gravity.)
• Why does the water squirt out once the lid is removed? (Air pressure enters from the top, allowing gravity to pull the water out through the holes.)
• How does this experiment demonstrate the role of atmospheric pressure? (It shows that air pressure is strong enough to hold water inside the bottle until a path for air is opened.)