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Plastic bottle filled with tinted red water being drawn on with a permanent marker

How To Make A Water Clock

Head back in time with this cool science experiment!

A clepsydra water clock is a water-based time telling contraption invented by the Ancient Greeks. Cool, right?! Find out how to make your own and get seriously geeky!

How To Make a Water Clock

  • Grab these materials…
  • 1/2L clear plastic bottle
  • Scissors
  • Drawing pin
  • Permanent marker
  • Food colouring
  • Stopwatch

Start by…

Finding the middle point of your bottle. With the help of an adult, grab your scissors and cut your bottle in two.

Person cutting a plastic bottle

Next you…

Take the lid off your bottle and lay it flat on a surface. Then get your drawing pin and make a small hole in the center of the lid. Get an adult to help you just in case.

Person using a drawing pin to make a hole in the lid of plastic bottle then screwing it back on


Screw the lid back onto the top half of the bottle. Turn the top half of the bottle upside down and place it in the bottom half of your bottle with the lid facing the bottom.

Person placing the top half of a plastic bottle upside down on the bottom half

After that..

Then add your food colouring to 500ml of water and keep your stopwatch close. 

Person pouring red food colouring into a glass of water

Almost there…

Pour your coloured water into the bottle's top half with the lid. Then time a minute and once that minute is up, take your marker and draw a line at the water level to indicate 1 minute. Then repeat and mark 2 minutes and so on. 

Person drawing on a plastic bottle filled with red water


When the water has passed through completely, your water clock is ready. Pour the water out and start again, but this time you won't need the stopwatch, just use your water clock to count the minutes. Genius!

Child holding their homemade water clock


Why not decorate your water clock using permamenet markers, glitter, paint – the options are endless and so is your creativity.

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