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Water Challenge

How to make a water clock

Find a use for an old plastic bottle by creating this clever clock…

Learn how to make a water clock in six easy steps with our easy tutorial. Not only will you learn about this ancient form of timekeeping, but you’ll be reusing an old plastic bottle — awesome!
How did people measure time before the invention of clocks or stopwatches? Well, the Ancient Greeks used a water clock called a clepsydra – and you can, too!

What you’ll need:

  • Large, clear plastic bottle
  • Round-edge scissors
  • Compass or drawing pin
  • Marker pen
  • Food colouring
  • Stopwatch

Step 1


First, roughly measure halfway down the bottle, then carefully cut the bottle in two using the scissors. This can be tricky, so ask an adult to help.

Step 2


Now, unscrew the top off the bottle and make a small hole in it using the compass – ask an adult to help. Then put the lid back on the bottle.

Step 3


Next, turn the top half of the bottle upside down and place it inside the bottom half, so that the bottle top is facing downwards.

Step 4


Now, mix a few drops of the food colouring into a pint of water, and then have your stopwatch at the ready!


Step 5


Pour the water into the top of the bottle and then start timing. Each time a minute passes, mark a line at the water level of the bottom bottle.

Step 6


Once all the water has passed into the bottom bottle, pour the water back into the top half and count off the minutes as the water pours down. Voila — your plastic bottle has transformed into an ancient timepiece!

Did you know?

Water clocks are thought to be one of the oldest time-measuring devices in the world – some have been found that date back to the 14th century B.C!



Time to drink up!

Water is an incredible natural resource. Not only can it be used for clever crafts like this water clock but it’s good for you, too. Drink up – glug, glug, glug!




Be a planet hero – recycle!