Further informationIs water blue?Water does absorb a tiny amount of light, but in small amounts, we don’t notice it. Water actually absorbs light that has a reddish color. When there’s a lot of water – like a whole lake full – we notice that red light from the Sun has actually been absorbed. So what color do we see when reddish light is gone?Blue!Blue is the color absorbed the least by water, so it’s the one we see the most. Blue light also scatters more than other light. That’s the reason why the sky is blue. That scattering affects the color of water too.It just takes a big enough sample of water to notice these things. That’s why you won’t see color in the glass you’re drinking.
ExplorationBlue Water (Through Milk)If you want to make the water in your drinking glass appear blue, you can actually do it by adding something white:Milk!A few drops of milk in a glass of water will make it appear slightly blue. That’s because the white milk is helping to scatter light and the blue light is scattering more than other colors.
Sources & links
Chaplin, Martin “Water Absorption Spectrum.” 7 June 2009. Water Structure and Science. 28 Jul 2009. <http://www.lsbu.ac.uk/water/vibrat.html> "industrial glass." Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 29 Jul. 2009 <http://www.britannica.com/EBchecked/topic/1426115/industrial-glass>.