Build your own rain gauge

This is a simple rain gauge that students can make on their own


Supplies needed to build a simple rain gauge
  • A plastic 2-litre pop bottle with straight sides
  • Ruler at least 15 centimetres in length
  • Scissors
  • Stones or large gravel
  • Clear tape
  • Water


  1. Cut the bottle about 10 centimetres from its top. Save the top part.
  2. Place stones or gravel in the bottom of the bottle until they fill the little bumps in the bottom and come up to the part of the bottle where the sides are straight. This wll add weight to the guage to make it more stable.
  3. Tape the ruler to the side of the bottle so that the zero mark on the ruler is a centimetre or two about the stones.
  4. Pour enough water into the bottle so that the water level is at the zero mark on the ruler.
  5. Take the top of the bottle (the part you cut off earlier), turn it upside down, and put it into the bottom portion so that it looks like a funnel.
  6. Set your guage in an open area away from trees or buildings, which may affect the amount of rain that falls into the bottle.
  7. When it has rained, take a reading using the ruler taped to the side of the bottle. Then pour out the excess water until the water level is once again at zero. (If you pour out too much water, simply add more until the water level again reaches zero on the ruler.)

Points to discuss

The final product of the activity, showing that the rocks used to anchor the gauge are covered in water and the ruler's zero measurement is at the water's surface

If you leave your rain guage out in the sun for a day, be sure to check the guage as some of the water may evaporate. If that happens, just add water until the level is at zero again.

As a further exercise, your students may want to tape a coffee filter into the funnel part of the gauge to collect any particles that fall into the gauge. The rainwater will drip through the filter and into the bottle eventually. Your students can then look at the filter through a microscope and see what it captured.

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