Every so often for bath time EC and YC like to add tablets that change the water colour. They like to see what colours they get when mixing them together, plus it is rather cool to have a different colour bath every once in a while. Because they really love doing this I thought it would be fun to do a science experiment based on colour mixing. This walking water science experiment is certainly eye catching that will leave everyone saying wow!  You can find our previous colour mixing activity here.

Make sure that you follow our STEM board on Pinterest for more ideas, and don’t forget to pin the Pin at the bottom.

You will need:

  • 6 clear glasses
  • Kitchen towel
  • Red, blue and yellow food colouring

Fill 3 of the glasses up with water.


Add one colour to each of these glasses.


Arrange the glasses so that there are empty ones between the ones with water.


Roll up your kitchen towels and then add them to each glass. There should be 2 bits coming out/in to everyone.

Over time the water will start moving up the towel and start filling up the empty glasses with coloured water. Consequently as the colours mix you will see the new ones appear.


I asked EC and YC to predict what they thought would happen and they successfully predicted that we would get new colours.



We left them over night and checked them before heading out to school. Both of them were really excited to see what had happened. EC asked if we could keep it out over the weekend to see if anything else happened. He thought that the glasses would carry on filling up. As it turned out, they didn’t. The water levels in the glasses stayed equal, but the kitchen towels absorbed more of the water.


The science behind it

The water moves up the paper towels because of capillary action. This is the movement of a liquid through or along the surface of another material in spite of other forces, such as gravity.

Pin for later:

walking water colour mixing science experiment