Soft Water Science Experiment: The Suds Shake Up

Funny little blonde looks on flasks with reagents

Try the Suds Shake Up with your family.

It’s about that time again – Kids everywhere are back in school for another year. During the 2014-2015 school year, they’ll make new friends, excel in clubs and they might even take part in a science fair. At Kinetico San Antonio, we have the perfect science experiment that can be easily tweaked for budding scientists of any age. We’re calling it The Suds Shake Up!


For younger participants: Did you know that water can be hard? No, we’re not talking about ice!

For older participants: Do you want cleaner clothes and appliances? The science behind soft water can make you a believer in the power of a water softener!

Needed Materials (Less than $20)

  • (2) Identical plastic water bottles with labels removed.
  • (1) Liquid dishwashing soap
  • (1) Permanent marker
  • (1) Eye dropper
  • (1) Stopwatch or timer
  • (1) Gallon of tap water
  • (1) Gallon of soft or distilled water
  • (1) Notebook to record findings


  1. Fill one bottle halfway with tap water and the other bottle halfway with distilled or soft water.
  2. Using the permanent marker, mark the top of the water on each bottle.
  3. Using the eyedropper, put (3) drops of liquid soap into each bottle of water and tightly close the lid.
  4. Have someone start the time when you say go. Shake the bottle with tap water for 20 seconds.
  5. Using the permanent marker, draw a line to mark where the top of the suds reached.
  6. Repeat 5 and 6 with the distilled or soft water.
  7. Measure the difference between the mark you made for the water line and mark you made for the suds on each bottle.
  8. Record the distance between the two lines in centimeters.
  9. Repeat steps 3-8 twice more for each bottle. Make sure to fill the water to the same water line.
  10. Take the average of the 3 distances for each bottle.
  11. Which water made bigger suds? Why? Answer these questions and describe the effect of hard water minerals on soap.

This science fair project is easy, inexpensive and (our favorite part) details the benefits of soft water in your home! What are your favorite science fair projects?