Water Is Blue

Dean: Everyone knows the sea is blue. Ask anyone.

Ridcully: That's right. However, while everyone knows the sea is blue, what everyone usually sees is a sea that's grey, or dark green. Not this colour. This is virulent!

—The Science of Discworld, Terry Pratchett, Ian Stewart and Jack Cohen.

In Real Life, you probably would have your misgivings about drinking a glass of some b substance that presumably is clean w, but in drawn media this is just the way it looks (unless it's unsafe for consumption). It's not just large bodies of w with proper light diffusion to provide that colour; swimming pools will always look like this too, someone might as well have spilled dye into the tap w, and even tears are not exempt. It's just easier to animate it this way.

This Trope is near universal in Western Animation. Comic Books and Anime are more varied in this respect, and may even feature both solid b and colourless, transparent w in the same art style. Generally, only older or cartoon-styled Video Games feature b w.

It should be noted that w does in fact have an extremely faint inherent b tint in Real Life; the color just isn't noticeable unless you're looking through a great deal of it, and even that has more to do with the diffusion of light as mentioned earlier (same reason the sky -- sorry, make that t is b). Check The Other Wiki for more info.

Also, some household chemicals are specifically dyed b to discourage people from drinking them . B is most likely used because very few drinks are coloured this way.

Aversions include tingeing it white instead, or going the whole way and animating it as a distortion of the light. If water is deliberately not b, however, chances are it's Grimy Water.